OBD2 Codes: Free Download, Lookup, Meaning, Fixes, Full List

Got your car scanned, found an OBD2 code, and want to know what it is?

Don’t worry! All car diagnostic codes are here for you to discover.

In this article, you’ll find what any OBD2 code means, the causes, symptoms, and how to fix it. We also offer code lists in PDF for free download.

Let’s go!!

All OBD2 Codes Lookup

Search below all generic and manufacturer-specific OBD2 fault codes and their meaning in most of the popular car makes such as Acura, Audi, BMW, Chevrolet, Dodge, Chrysler, Jeep, Ford, Honda, Hyundai, Infiniti, Isuzu, Jaguar, KIA, Land Rover, Lexus, Mazda, Mitsubishi, Nissan, Subaru, Toyota, and VW, etc.


What is an OBD2 Code?

obd2 codes samples
Samples of OBD2 Codes detected with OBD Auto Doctor software

OBD is short for onboard diagnostics. It refers to a vehicle’s electronic system that performs self-diagnosis and reporting. Whenever a problem is detected, the system records it as a unique code. That code is known as a diagnostic trouble code (DTC). As a vehicle owner or mechanic, you can pull that code and interpret it to understand the nature of the problem. For example, if the car gives you the P0201 code, it means that there’s a malfunction in cylinder 1 of the injector circuit. Your job is to pinpoint the issue and fix it.

Now, with that in mind, OBDII codes are trouble codes specific to OBD2 vehicles. These are generally cars, SUVs, light trucks, etc., made/sold in the US since 1996. In other words, if an automobile is a 1996 or newer model, it is OBD2-compliant. And that also means that it uses OBD-II codes to do self-diagnosis and reporting. I’ll be using all three interchangeably all through the post, be sure not to get confused.

How to Read OBD2 Codes

OBD provides monitoring for various systems. They include the engine control module, body, chassis, etc. When you look at an OBD2 code, you can immediately tell where the fault is by reading the letters and numbers it contains. Below is a breakdown.

Explanation of OBD2 codes
How to read OBD2 code by reading the letters and numbers it contains

The First Character (Letter)

All OBDII codes start with a letter that denotes the part of the vehicle that has a fault. Let’s check it out, shall we?

P – Powertrain. It includes the engine, transmission, and all the associated accessories.

U – Network & Vehicle Integration. These are functions that are managed and shared by onboard computer systems.

B – Body. These are parts mainly found in the passenger compartment area.

C – Chassis. It covers mechanical systems and functions like steering, suspension, and braking.

The Second Character (Number)

A number usually follows the first letter. This number can only be ‘0’, ‘1’, ‘2’, or ‘3’.

0 – If it’s a ‘0’, ‘2’, or ‘3’, the code is a standardized (SAE) code; also known as generic code

1 – If it’s a ‘1’, you’re looking at a manufacturer-specific code

The Third Character (Number/Letter)

This number denotes the particular vehicle system that has a fault. There are eight systems in total:

0 – Fuel and air metering and auxiliary emission controls

1 – Fuel and air metering

2 – Fuel and air metering (injector circuit)

3 – Ignition systems or misfires

4 – Auxiliary emission controls

5 – Vehicle speed control and idle control systems

6 – Computer and output circuit

7 – Transmission

A-F – Hybrid Trouble Codes

The Fourth And Fifth Characters (Number)

The final piece of a DTC is a two-digit number. This number defines the exact problem that you’re dealing with. It can be any number between 0 and 99.

As you can see, a typical DTC has five characters in total, and each one of those characters gives it a description. For example, if you get the code P0219, it means that the car has an engine over-speed condition.

The ‘P’ means that the problem is in the powertrain. The ‘0’ means that it’s a generic code, while the ‘2’ refers to the fuel and air metering (injector circuit) system. The last two digits (19) define the problem, i.e., an over-speed condition.

Want to know more about codes and their meanings? Below is a more comprehensive OBD codes list.As mentioned already, DTC codes that start with ‘P’ relate to the powertrain. Those that begin with ‘U’ are for the network and vehicle integration system. The letter ‘B’ refers to the vehicle’s body, while ‘C’ is for the chassis.


Bonus: Best Professional OBD2 Scanners for DIY 2021

Meaning and Fix guide of OBD2 codes
DTC codes that start with ‘P’ relate to the powertrain. Those that begin with ‘U’ are for the network and vehicle integration system. The letter ‘B’ refers to the vehicle’s body while ‘C’ is for the chassis.

OBD2 Codes List PDF for FREE Download

Generic Powertrain OBD2 Trouble Codes List PDF

Generic Chassis, Network, and Body Codes [PDF]

Manufacturer-Specific OBD2 Codes [PDF]

To download your vehicle OBD2 code list, click the link you want:

OBD2 Codes

Below are the details of the top popular OBDII codes with meaning, causes, and fixes.

P0010 Intake Camshaft Position Actuator Circuit / Open (Bank 1)

The P0010 code happens when the ‘bank 1’ camshaft and the crankshaft have a mechanical timing variation. The problem occurs when the engine experiences high RPM. The ECM doesn’t correctly adjust valve lift at high RPM.

Main Symptoms:

  • Check Engine Light comes on
  • The engine performs poorly at high RPM
  • Car runs roughly
  • Lower fuel economy
  • Car fails the emission test

Possible Causes:

  • Sludge in engine oil
  • Faulty OVC (oil control valve)
  • Internal damage to ECM
  • ECM timing is out of sync
  • Wiring damage
  • Malfunction of crankshaft or camshaft sensor
  • A short in VCT/VVT circuit or the circuit is open

Diagnostic Steps:

  • Use an advanced diagnostic tool to pull engine codes
  • Inspect the VVT/VCT solenoid system for dirty oil
  • Inspect the circuit for wiring problems

Read more

P0011 Intake Camshaft Position Timing – Over-Advanced (Bank 1)

The P0011 code is triggered when the camshaft timing for bank 1 is above the limit set by the ECM. This situation causes an over-advanced condition that occurs either during retarding or advancing the camshaft timing.

Main Symptoms:

  • Check Engine Light comes on
  • Hard starting
  • Poor idle
  • Car may run rough or stall
  • Poor fuel economy
  • Car may fail an emission test

Possible Causes:

  • Camshaft remains advanced despite ECM commanding it to retard
  • Bank 1 oil control solenoid may be clogged or stuck
  • Oil may be too thick and is thus blocking passages in bank 1
  • Wiring problems in VCT/VVT
  • Oil continuously flows to VCT piston chambers open

Diagnostic Steps:

  • Check that engine oil is clean and has the recommended viscosity
  • Visually inspect the wiring in the CVT system
  • Pull engine codes and live data using an advanced diagnostic tool

Read more

P0012 Intake Camshaft Position Timing – Over-Retarded (Bank 1)

The P0012 code is triggered when bank 1 has an over-retarded timing condition that occurs either during retarding or advancing.

Main Symptoms:

  • Check Engine Light comes on
  • Hard starting
  • Poor fuel economy
  • Car may run rough or stall
  • Car may fail an emission test

Possible Causes:

  • Camshaft timing is incorrect
  • Wiring problems in VCT/VVT
  • Oil continuously flows to the VCT piston chamber
  • Timing valve solenoid control has failed and is stuck in the open position
  • Oil may be too thick and is thus blocking passages in bank 1

Diagnostic Steps:

  • Check that engine oil is clean
  • Visually inspect the wiring in the CVT system
  • Pull engine codes and live data using an advanced diagnostic tool
  • Using the bidirectional scanner, command the timing valve solenoid control valve to open and close, then see if camshaft timings change. If they change, it means the valve is not the problem

Read more

P0014 Exhaust Camshaft Position Timing – Over-Advanced (Bank 1)

The P0014 code happens when bank 1 camshaft has an over-advanced timing condition that occurs either during retarding or advancing.

Main Symptoms:

  • Check Engine Light comes on
  • Hard starting
  • Poor fuel economy
  • Car may run rough or stall
  • Car may fail emission test

Possible Causes:

  • Camshaft timing is incorrect
  • Wiring problems in VCT/VVT
  • Oil continuously flows to the VCT piston chamber
  • Timing valve solenoid control has failed and is stuck in the open position
  • Oil may be too thick and is thus blocking passages in bank 1

Diagnostic Steps:

  • Check that engine oil is clean and full in the tank
  • Visually inspect the wiring in the CVT system
  • Pull engine codes and live data using the advanced diagnostic tool

Using the bidirectional scanner, command the timing valve solenoid control valve to open and close, then see if camshaft timings change. If they change, it means the valve is not the problem

Read more

P0016 Crankshaft Position Camshaft Position Correlation Bank 1 Sensor A

The P0016 code occurs when the crankshaft and camshaft signals are out of time. Meaning the ECM can detect that the crankshaft’s timing and that of the camshaft do not correlate.

Main Symptoms:

  • Check Engine Light comes on
  • The engine may crank but fail to start
  • The engine may continue to run but will record poor performance
  • Rattling sound in the harmonic balancer
  • Poor fuel economy

Possible Causes:

  • The timing chain is overstretched
  • Tone ring on the camshaft and/or crankshaft is has slipped or broken
  • Timing chain has jumped teeth and put camshaft timing out of position
  • Problems with camshaft phaser and putting the phaser out of position
  • Wiring to crank/cam sensor is damaged

Diagnostic Steps:

  • Inspect oil control valve (OCV) for connection or wiring problems
  • Check that engine oil is clean, full, and has the correct viscosity
  • Pull engine codes and live data using an advanced diagnostic tool
  • Using the bidirectional scanner, command the OVC on and off, then see if camshaft timings change. If they change, it means the valve is not the problem

Read more

P0037 Heated Oxygen Sensor (H02S) Heater Control Circuit Bank 1 Sensor 2

The P0037 code is triggered when bank 1, sensor 2 of the O2 sensor heater circuit is faulty. For example, the engine isn’t achieving a closed-loop and causes the car to increase emissions.

Main Symptoms:

  • Check Engine Light comes on
  • Longer time needed to achieve a closed-loop
  • Decreased fuel economy
  • The engine may go into the fixed fuel mix

Possible Causes:

  • H02S sensor in bank 1, circuit 2 is not sending the correct signal to ECM
  • Damaged or failed element in the heater circuit
  • Open in O2 sensor heater’s circuit
  • Open/short in O2 sensor heater’s battery
  • Defective ECM (this is the least likely cause)

Diagnostic Steps:

  • Inspect wiring and power to the O2 sensor and ensure there’s no damage/open/short
  • Use code reader to pull engine codes
  • Check the voltage of the O2 sensor and ensure it matches the manufacturer’s specs
  • Replace O2 sensor if necessary

Read more

P0102 Mass or Volume Air Flow Circuit low Input

The P0102 code happens when the mass airflow (MAF) sensor does not perform within the standard expectation and sends a lower signal than usual (due to low voltage).

Main Symptoms:

  • Check Engine Light comes on
  • Extremely low fuel consumption and thus internal engine problems
  • Engine runs roughly
  • Car idles and stalls frequently

Possible Causes:

  • Defective MAF sensor
  • Presence of dirt and debris in MAF (restricts airflow)
  • Leaks in the air intake system
  • Improper wiring of the circuit to MAF sensor

Diagnostic Steps:

  • Use code reader to pull engine codes
  • Visually inspect MAF sensor wiring and circuit
  • Check for air leaks in the air intake system
  • Inspect MAF to see if there are dirt and debris

Read more

P0106 Manifold Absolute Pressure/Barometric Pressure Circuit Range/Performance Problem

The P0106 code is triggered when the Powertrain Control Module (PCM) has not detected a change in engine speed, throttle angle, and exhaust gas recirculation (EGR) despite an increase in manifold absolute pressure (MAP). An increase in MAP indicates an increase in engine load.

Main Symptoms:

  • Check Engine Light comes on
  • Poor fuel economy
  • Engine fails to idle
  • The engine produces black smoke (visible at tailpipe)
  • Erratic acceleration

Possible Causes:

  • Faulty MAP sensor
  • The air intake component is loose, cracked, or doesn’t have its plastic fitting
  • Water or dirt affecting connector to MAP sensor
  • Corrosion may be causing the poor signal to and from the MAP sensor
  • PCM is defective (least likely but not unlikely)

Diagnostic Steps:

  • Use an advanced scanner to pull engine codes.
  • With that scanner, diagnose the MAP sensor when the engine is off and the key is on. It should be similar or close to barometric pressure (BARO) reading.
  • Start the engine and see if MAP sensor readings drop significantly. If they do, the sensor is working correctly.

Read more

P0113 Intake Air Temperature Circuit High Input (Sensor 1)

P0113 means that the signal voltage from the intake air temperature (IAT) is above 5V, which is more than the expected range.

Main Symptoms:

  • Check Engine Light comes on
  • The engine may run extra lean

Possible Causes:

  • Defective IAT sensor
  • Loose or faulty wiring at IAT sensor
  • Open or short in IAT ground circuit, signal circuit, or reference circuit
  • PCM is defective (least likely but not unlikely)

Diagnostic Steps:

  • Use an advanced scanner to pull engine codes.
  • View live data from the IAT sensor. If the result is less than -30 degrees Celsius, then the sensor is likely to be faulty. Otherwise, it’s probably an intermittent problem.
  • Check the wiring for opens and loose connections.

Read more

P0118 Engine Coolant Temperature Circuit High Input

P0118 means that the PCM has determined that ECT is less than freezing temp, yet the engine has been running for several minutes, which shouldn’t happen.

Main Symptoms:

  • Check Engine Light comes on
  • Poor fuel economy
  • The engine fails to idle and may not start completely
  • The engine produces black smoke (visible at tailpipe)

Possible Causes:

  • Defective ECT sensor
  • Open or short in ECT signal or ground circuit
  • PCM is defective (least likely but not unlikely)

Diagnostic Steps:

  • Using an OBD2 scanner, check the ECT. If it’s a logical reading, the problem is intermittent.
  • Perform a wiggle test while looking out for drop-outs. If there are any, there’s a bad connection to or from the ECT sensor.

Read more

P0121 Throttle/Pedal Position Sensor/Switch A Circuit Range/Performance Problem

P0121 happens when the PCM has detected that the throttle position sensor (TPS) voltage is more or less than it should be for the current RPM.

Main Symptoms:

  • Check Engine Light comes on
  • The car produces black smoke (visible at tailpipe)
  • Car stumbles when you accelerate or decelerate
  • The engine may fail to start completely

Possible Causes:

  • Defective TPS
  • Open or short in TPS circuit
  • Loose or bad connection to TPS
  • PCM is defective (least likely but not unlikely)

Diagnostic Steps:

  • Visually inspect all wiring to TPS for loose, open, or short connections

Using an OBD2 scanner, check for live data and freeze-frame data from TPS. If it doesn’t read 0.5 at idle and 4.5 at full throttle, the TPS is faulty

Read more

P0122 Throttle/Pedal Position Sensor/Switch A Circuit Low Input

P0122 means that the PCM reports that the TPS has recorded a lower voltage than the minimum limit. The value varies from one car to another, but the code may come when the voltage hits 0.20V or less.

Main Symptoms:

  • Check Engine Light comes on
  • Extremely high idle
  • Rough or low idle
  • Car stalls
  • Acceleration is low or completely lacking

Possible Causes:

  • Defective TPS
  • Open or short in TPS circuit
  • Improper mounting of TPS after replacement
  • TPS has loosened
  • PCM is defective (least likely but not unlikely)

Diagnostic Steps:

  • Visually inspect all wiring to TPS for loose, open, or poor connections.
  • Check that TPS is tightly in position, especially if you recently replaced it.

Read more

P0128 Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature)

P0128 OBD2 code means the PCM has detected that the engine has not attained the required temperature despite it is on for enough time to reach that temperature.

Main Symptoms:

  • Check Engine Light MAY come on
  • Engine temp drops when the vehicle is in high speed
  • Engine takes abnormally long to warm

Possible Causes:

  • Most likely cause is that thermostat is leaking or stuck in open position
  • Engine coolant level is too low
  • Defective IAT sensor
  • Defective ECT sensor
  • Defective cooling fan

Diagnostic Steps:

  • Check whether coolant strength and level are in the recommended range
  • Check whether IAT sensor, ECT sensor and coolant fan are working
  • If all the above are okay then the thermostat is the problem

Read more

P0131 O2 Sensor Circuit Low Voltage (Bank 1 Sensor 1)

P0131 triggers when the ECM has determined a low voltage condition in bank 1 sensor 1; i.e., O2 sensor voltage remained too low for longer than 2 minutes.

Main Symptoms:

  • Check Engine Light comes on
  • The car produces black smoke (visible at tailpipe)
  • Poor fuel economy
  • The engine may fail to start completely
  • If it starts, it may run rough and/or stumble

Possible Causes:

  • Mostly a problem related to corrosion, loose terminal, or burnt wire in the O2 sensor 1 connector
  • Defective O2 sensor
  • Open or short in the wiring to the O2 sensor
  • O2 circuit is experiencing high resistance

Diagnostic Steps:

  • Visually inspect all wiring to O2 sensor 1 for loose, open, or short connections
  • Use a wiggle test to determine where the voltage drops out
  • Using an OBD2 scanner, check whether sensor 1 of bank 1 is switching properly

Read more

P0133 O2 Sensor Circuit Slow Response (Bank 1 Sensor 1)

P0133 occurs when the O2 sensor or ECM can’t adjust the air to fuel ratio as it’s supposed to even when the engine is running.

Main Symptoms:

  • Generally doesn’t come with symptoms. However, in some cases, the Check Engine Light may come on, and fuel economy may reduce

Possible Causes:

  • The first O2 sensor in bank 1 is faulty
  • Short, open, or broken wire in the O2 sensor circuit
  • Exhaust leak

Diagnostic Steps:

  • Visually inspect all wiring to the first O2 sensor for loose, open, or short connections
  • • Use a wiggle test to determine where the voltage drops out
  • • Visually check for exhaust leaks or air inlet leaks
  • • Using an OBD2 scanner, check whether sensor 1 of bank 1 is switching properly

Read more

P0135 O2 Sensor Heater Circuit Malfunction (Bank 1 Sensor 1)

Usually, when the O2 heater attains operating temperature, the O2 sensor switches based on ambient temp. If ECM determines that the O2 sensor took too long to switch, this code is set. It applies to the first sensor of bank 1

Main Symptoms:

  • Check Engine Light comes on
  • Poor fuel economy

Possible Causes:

  • Short, open, or broken wire in O2 heating system
  • High resistance in O2 heater element or circuit

Diagnostic Steps:

  • Visually inspect all wiring to the first O2 sensor (bank 1) for loose, open, or short connections
  • Use a wiggle test to determine where the voltage drops out
  • If the code is persistent, replace the O2 sensor

Read more

P0136 O2 Sensor Circuit Malfunction (Bank 1 Sensor 2)

P0136 means that the ECM has determined a low voltage condition in bank 1 sensor 2; i.e., O2 sensor voltage remained too low for longer than 2 minutes.

Main Symptoms:

  • Check Engine Light comes on
  • The car produces black smoke (visible at tailpipe)
  • Poor fuel economy
  • The engine may fail to start completely
  • If it starts, it may run rough and/or stumble

Possible Causes:

  • Mostly a problem related to corrosion, loose terminal, or burnt wire in the O2 sensor 2 connector
  • Defective O2 sensor
  • Open or short in the wiring to the O2 sensor
  • O2 circuit is experiencing high resistance

Diagnostic Steps:

  • Visually inspect all wiring to O2 sensor 2 for loose, open, or short connections
  • Use a wiggle test to determine where the voltage drops out
  • Using an OBD2 scanner, check whether sensor 2 of bank 1 is switching properly

Read more

P0137 O2 Sensor Circuit Low Voltage (Bank 1 Sensor 2)

Basically the same as P0136. The P0137 is triggered when the PCM has detected that the O2 sensor may be inactive.

Main Symptoms:

  • Generally doesn’t come with symptoms. However, in some cases, the Check Engine Light may come on, and fuel economy may reduce

Possible Causes:

  • Faulty O2 sensor
  • Short, open, or broken wire in the O2 sensor circuit
  • Defective heater circuit in the O2 sensor
  • High resistance in O2 heater element or circuit
  • Faulty fuel pump regulator resulting in very high or very low fuel pressure
  • Exhaust leak

Diagnostic Steps:

  • Visually inspect all wiring to O2 sensor for loose, open, or short connections
  • Use a wiggle test to determine where the voltage drops out
  • Visually check for exhaust leaks or air inlet leaks
  • If the code is persistent, replace the O2 sensor

Read more

P0138 O2 Sensor Circuit High Voltage (Bank 1 Sensor 2)

The P0138 code means the heated O2 sensor in bank 1 sensor 2 gives a higher voltage reading than it should. For most vehicles, the code comes when voltage exceeds 1.5V.

Main Symptoms:

  • Generally doesn’t come with symptoms. However, in some cases, the Check Engine Light may come on, and fuel economy may reduce

Possible Causes:

  • Fuel temp is excessively high
  • Short, open, or broken wire in the O2 sensor circuit

Diagnostic Steps:

  • Visually inspect all wiring to O2 sensor for loose, open, or short connections
  • Use a wiggle test to determine where the voltage drops out
  • Using an OBD2 scanner, check whether sensor 1 of bank 2 is switching properly

Read more

P0141 O2 Sensor Heater Circuit Malfunction (Bank 1 Sensor 2)

P0141 means when the O2 heater attains operating temperature, the O2 sensor switches based on ambient temp. If ECM determines that the O2 sensor took too long to switch, this code is set. It applies to the second sensor of bank 1.

Main Symptoms:

  • Check Engine Light comes on
  • Poor fuel economy

Possible Causes:

  • Short, open, or broken wire in O2 heating system
  • High resistance in O2 heater element or circuit

Diagnostic Steps:

  • Visually inspect all wiring to the second O2 sensor (bank 1) for loose, open, or short connections
  • Use a wiggle test to determine where the voltage drops out
  • If the code is persistent, replace the O2 sensor

Read more

P0161 O2 Sensor Heater Circuit Malfunction (Bank 2 Sensor 2)

P0161 triggers when the O2 heater attains operating temperature, O2 sensor switches based on ambient temp. If ECM determines that the O2 sensor took too long to switch, this code is set. It applies to the second sensor of bank 2.

Main Symptoms:

  • Check Engine Light comes on
  • Poor fuel economy

Possible Causes:

  • Short, open, or broken wire in O2 heating system
  • High resistance in O2 heater element or circuit

Diagnostic Steps:

  • Visually inspect all wiring to the second O2 sensor (bank 2) for loose, open, or short connections
  • Use a wiggle test to determine where the voltage drops out
  • If the code is persistent, replace the O2 sensor

Read more

P0171 System Too Lean (Bank 1)

P0171 indicates that there is a lean condition in bank 1; i.e., there’s excess oxygen in the exhaust

Main Symptoms:

  • Significant decrease in engine power
  • Car hesitates then surges upon acceleration
  • Rough idle

Possible Causes:

  • Dirty or defective MAF sensor
  • MAF sensor has a vacuum leak
  • Positive Crankcase Ventilation (PCV) valve is stuck in the open position
  • Leak either in PCV or vacuum system

Diagnostic Steps:

  • Inspect MAF sensor in bank 1 for dirt and debris
  • Check whether fuel pressure is correct
  • Check vacuum and PCV for leaks
  • Run a smog test using an OBD2 scanner

Read more

P0172 System Too Rich (Bank 1)

P0172 happens when there’s a rich condition in bank 1; i.e., there’s too little oxygen in the exhaust condition in bank 1; i.e., there’s excess oxygen in the exhaust.

Main Symptoms:

  • Generally doesn’t come with symptoms, but the Check Engine Light may come on, and the engine may misfire

Possible Causes:

  • Dirty or defective MAF sensor
  • MAF sensor has a vacuum leak
  • The problem relating to fuel pressure or delivery

Diagnostic Steps:

  • Inspect MAF sensor in bank 1 for dirt and debris
  • Check whether fuel pressure is correct
  • Inspect fuel lines and injectors for any leaks/openings and dirt
  • Check vacuum, PCV, and exhaust for leaks
  • Run a smog test using an OBD2 scanner

Read more

P0174 System Too Lean (Bank 2)

This code means that there’s a lean condition in bank 2; i.e., there’s excess oxygen in the exhaust

Main Symptoms:

  • Significant decrease in engine power
  • Car hesitates then surges upon acceleration
  • Rough idle

Possible Causes:

  • Dirty or defective MAF sensor
  • MAF sensor has a vacuum leak
  • Positive Crankcase Ventilation (PCV) valve is stuck in the open position
  • Leak either in PCV or vacuum system

Diagnostic Steps:

  • Inspect MAF sensor in bank 2 for dirt and debris
  • Check whether fuel pressure is correct
  • Check vacuum and PCV for leaks
  • Run a smog test using an OBD2 scanner

Read more

P0300 Random/Multiple Cylinder Misfire Detected

When the code P0300 is triggered, it means that PCM has detected that there’s an engine cylinder that’s not firing properly. It could be one or more cylinders. PCM hasn’t specified the exact cylinder

Main Symptoms:

  • Check Engine Light comes on
  • Check Engine Light may flash
  • Engine lacks power
  • The engine may be hard to start
  • The engine may stumble and hesitate frequently

Possible Causes:

  • Defective or worn out spark plugs
  • Low fuel pressure
  • Vacuum leak
  • Defective catalytic converter
  • Defective fuel injector
  • Defective coil
  • Bad camshaft position sensor
  • Defective crankshaft sensor
  • Problem with distributor

Diagnostic Steps:

  • Using a scan tool, pull codes and see if there are any other besides P0300. Address the others first
  • Inspect whether there are loose, open, or short wires in ignition coils
  • Inspect whether spark plugs and their wires are in good condition
  • Check that fuel pressure is within the recommended range
  • Inspect fuel injectors to see whether they are in good condition

Read more

P0301 Cylinder 1 Misfire Detected

The meaning of P0301 is that the PCM has detected that cylinder #1 is not firing properly.

Main Symptoms:

  • Check Engine Light comes on
  • Check Engine Light may flash
  • Engine lacks power
  • The engine may be hard to start
  • The engine may stumble and hesitate frequently

Possible Causes:

  • Defective or worn out spark plugs in cylinder 1
  • Low fuel pressure
  • Vacuum leak
  • Defective catalytic converter
  • Defective fuel injector
  • Defective coil
  • Defective camshaft position sensor
  • Defective crankshaft sensor
  • Problem with distributor

Diagnostic Steps:

  • Using a scan tool, pull codes and see if there are any other besides P0301. Address the others first
  • Inspect whether there are loose, open, or short wires in ignition coils in cylinder 1
  • Inspect whether cylinder 1 spark plugs and their wires are in good condition
  • Check that fuel pressure is within the recommended range
  • Inspect fuel injectors to see whether they are in good condition

Read more

P0302 Cylinder 2 Misfire Detected

P0302 indicates that the PCM has detected that cylinder #2 is not firing properly

Main Symptoms:

  • Check Engine Light comes on
  • Check Engine Light may flash
  • Engine lacks power
  • The engine may be hard to start
  • The engine may stumble and hesitate frequently

Possible Causes:

  • Defective or worn out spark plugs in cylinder 2
  • Low fuel pressure
  • Vacuum leak
  • Defective catalytic converter
  • Defective fuel injector
  • Defective coil
  • Defective camshaft position sensor
  • Defective crankshaft sensor
  • Problem with distributor

Diagnostic Steps:

  • Using a scan tool, pull codes and see if there are any other besides P0302. Address the others first
  • Inspect whether there are loose, open, or short wires in ignition coils in cylinder 2
  • Inspect whether cylinder 2 spark plugs and their wires are in good condition
  • Check that fuel pressure is within the recommended range
  • Inspect fuel injectors to see whether they are in good condition

Read more

P0303 Cylinder 3 Misfire Detected

The P0303 code occurs when the PCM has detected that cylinder #3 is not firing properly.

Main Symptoms:

  • Check Engine Light comes on
  • Check Engine Light may flash
  • Engine lacks power
  • The engine may be hard to start
  • The engine may stumble and hesitate frequently

Possible Causes:

  • Defective or worn out spark plugs in cylinder 3
  • Low fuel pressure
  • Vacuum leak
  • Defective catalytic converter
  • Defective fuel injector
  • Defective coil
  • Defective camshaft position sensor
  • Defective crankshaft sensor
  • Problem with distributor

Diagnostic Steps:

  • Using a scan tool, pull codes and see if there are any other besides P0303. Address the others first
  • Inspect whether there are loose, open, or short wires in ignition coils in cylinder 3
  • Inspect whether cylinder 3 spark plugs and their wires are in good condition
  • Check that fuel pressure is within the recommended range
  • Inspect fuel injectors to see whether they are in good condition

Read more

P0304 Cylinder 4 Misfire Detected

The P0304 code is triggered when the PCM has detected that cylinder #4 is not firing properly.

Main Symptoms:

  • Check Engine Light comes on
  • Check Engine Light may flash
  • Engine lacks power
  • The engine may be hard to start
  • The engine may stumble and hesitate frequently

Possible Causes:

  • Defective or worn out spark plugs in cylinder 4
  • Low fuel pressure
  • Vacuum leak
  • Defective catalytic converter
  • Defective fuel injector
  • Defective coil
  • Defective camshaft position sensor
  • Defective crankshaft sensor
  • Problem with distributor

Diagnostic Steps:

  • Using a scan tool, pull codes and see if there are any other besides P0304. Address the others first
  • Inspect whether there are loose, open, or short wires in ignition coils in cylinder 4
  • Inspect whether cylinder 4 spark plugs and their wires are in good condition
  • Check that fuel pressure is within the recommended range
  • Inspect fuel injectors to see whether they are in good condition

Read more

P0305 Cylinder 5 Misfire Detected

The P0305 code indicates that the PCM has detected that cylinder #5 is not firing properly.

Main Symptoms:

  • Check Engine Light comes on
  • Check Engine Light may flash
  • Engine lacks power
  • The engine may be hard to start
  • The engine may stumble and hesitate frequently

Possible Causes:

  • Defective or worn out spark plugs in cylinder 5
  • Low fuel pressure
  • Vacuum leak
  • Defective catalytic converter
  • Defective fuel injector
  • Defective coil
  • Defective camshaft position sensor
  • Defective crankshaft sensor
  • Problem with distributor

Diagnostic Steps:

  • Using a scan tool, pull codes and see if there are any other besides P0305. Address the others first
  • Inspect whether there are loose, open, or short wires in ignition coils in cylinder 5
  • Inspect whether cylinder 5 spark plugs and their wires are in good condition
  • Check that fuel pressure is within the recommended range
  • Inspect fuel injectors to see whether they are in good condition

Read more

P0306 Cylinder 6 Misfire Detected

The P0306 code is triggered when the PCM has detected that cylinder #6 is not firing properly.

Main Symptoms:

  • Check Engine Light comes on
  • Check Engine Light may flash
  • Engine lacks power
  • The engine may be hard to start
  • The engine may stumble and hesitate frequently

Possible Causes:

  • Defective or worn out spark plugs in cylinder 6
  • Low fuel pressure
  • Vacuum leak
  • Defective catalytic converter
  • Defective fuel injector
  • Defective coil
  • Defective camshaft position sensor
  • Defective crankshaft sensor
  • Problem with distributor

Diagnostic Steps:

  • Using a scan tool, pull codes and see if there are any other besides P0306. Address the others first
  • Inspect whether there are loose, open, or short wires in ignition coils in cylinder 6
  • Inspect whether cylinder 6 spark plugs and their wires are in good condition
  • Check that fuel pressure is within the recommended range
  • Inspect fuel injectors to see whether they are in good condition

Read more

P0316 Misfire Detected On Startup (First 1000 Revolutions)

The P0316 code occurs when the PCM has detected a misfire of less than 1,000 revolutions after startup.

Main Symptoms:

  • Check Engine Light comes on
  • Engine lacks power
  • Rough idle

Possible Causes:

  • Defective or worn out spark plugs
  • No fuel
  • Low fuel pressure
  • Vacuum leak
  • Defective catalytic converter
  • Defective fuel injector
  • Defective coil
  • Defective crankshaft sensor
  • Wiring fault in the crankshaft position sensor
  • Problem with PCM

Diagnostic Steps:

  • Pull all codes, then address other misfire codes first
  • Check all wiring and connectors in crankshaft and camshaft position sensors
  • Review freeze frame data to narrow down the problem further

Read more

P0325 Knock Sensor 1 Circuit Malfunction (Bank 1 or Single Sensor)

The P0325 code is triggered when the PCM has detected that the engine’s knock sensor 1 in-circuit bank 1 is not working properly.

Main Symptoms:

  • Generally doesn’t come with symptoms, but Check Engine Light may come on.
  • The engine may also lose power

Possible Causes:

  • The first sensor in circuit bank 1 may be faulty
  • Open or short in the wiring to the sensor
  • Problem with engine coolant
  • The engine is excessively lean
  • PCM has failed (least likely)

Diagnostic Steps:

  • Visually inspect all wiring to knock sensor 1 in circuit bank 1. Ensure there are no shorts or open wires
  • View coolant temp data to check for issues
  • If there are none, clear the code and test drive the car. If it comes back, the sensor is defective

Read more

P0335 Crankshaft Position Sensor A Circuit Malfunction

The P0335 code happens when the PCM has detected that the crankshaft position (CKP) sensor does not produce pulses or the pulses are not normal. It uses these pulses to determine the position of the crankshaft.

Main Symptoms:

  • Check Engine Light comes on
  • The engine may fail to start
  • The vehicle may run rough

Possible Causes:

  • Defective CKP sensor
  • Open or short in CKP sensor wiring
  • The timing belt is broken
  • PCM has failed (least likely)

Diagnostic Steps:

  • Start by checking if there’s an RPM signal (using a scanner)
  • If it’s not there, check all the wires and connectors to the sensor. Repair as necessary
  • Check the sensor’s resistance and compare it with the manufacturer’s recommendation. If they don’t match, replace the sensor

Read more

P0340 Camshaft Position Sensor Circuit Malfunction

This OBD2 code means that there’s a problem with the camshaft position sensor (CPS) circuit. As such, PCM can’t perform ignition spark and fuel injector timing properly.

Main Symptoms:

  • Check Engine Light comes on
  • The engine may fail to start
  • The vehicle may run rough
  • Rough idle
  • Misfire

Possible Causes:

  • Defective CPS
  • Open or short in CPS wiring
  • Defective CKP sensor
  • PCM has failed (least likely)

Diagnostic Steps:

  • Inspect wiring to CPS and ensure there are no open or broken wires
  • Check CPS voltage if it’s within the manufacturer’s specs. If it is not, replace the sensor
  • Check CKP sensor as well to determine whether it’s the source of the problem

Read more

P0401 Exhaust Gas Recirculation Flow Insufficient Detected

This code indicates that the PCM has detected an insufficient amount of EGR.

Main Symptoms: The most notable symptom is engine pinging when the vehicle is at high speed or under load

Possible Causes:

  • Defective differential pressure feedback EGR (DPFE) sensor
  • Defective EGR valve
  • EGR valve can’t open because of lack of vacuum
  • Blockage in EGR tube

Diagnostic Steps:

  • Check the EGR valve and its tubing for deposits
  • Check DPFE sensor voltage to ensure its within a specified range
  • If not, replace the sensor. If it is, replace the EGR valve

Read more

P0420 Catalyst System Efficiency Below Threshold (Bank 1)

P0420 means the Catalytic converter is not working as efficiently as it should, and the vehicle is therefore emitting more harmful substances.

Main symptoms:

  • Check Engine Light comes on
  • Engine lacks power
  • Reduced fuel economy

Possible Causes:

  • Defective O2 sensor
  • Defective engine coolant temp
  • Wiring to downstream O2 sensor is damaged or improperly done
  • Leaking fuel injector
  • Oil is contaminated
  • Using leaded fuel where unleaded fuel was required
  • Defective catalytic converter, exhaust pipe, muffler, or exhaust manifold

Diagnostic Steps:

  • Inspect exhaust system for damage and leaks.
  • Check the voltage of the downstream O2 sensor while the engine is running. If it’s not steady (jumpy between .1 and .9 V), the catalytic converter needs replacing.

Read more

Bonus: How to Test an O2 Sensor with a Scan Tool

P0440 Evaporative Emission Control System Malfunction

The code P0440 means a component in the EVAP system is not working properly

Main Symptoms: Check Engine Light may come on

Possible Causes:

  • The gas cap is not working or has not been installed properly
  • The canister is plugged and defective
  • Purge solenoid has failed

Diagnostic Steps:

  • Inspect gas cap to see if it’s installed tightly
  • Check for disconnected or cracked EVAP hoses
  • Inspect the charcoal canister and fuel tank for leaks and damages
  • Check that the purge valve (solenoid) has no leaks

Read more

P0441 Evaporative Emission Control System Incorrect Purge flow

P0441 code is triggered when the PCM finds that there’s no purge flow (i.e., purge control valve is still closed) despite commanding a purge

Main Symptoms:

  • Check Engine Light may come on
  • Rough or erratic idle

4. Possible Causes:

  • Loose or damaged EVAP hoses
  • Defective purge valve
  • The gas cap is loose, missing, or damaged
  • The charcoal canister is damaged or defective

5. Diagnostic Steps:

  • Inspect gas cap to see if it’s installed tightly
  • Check for disconnected or cracked EVAP hoses
  • Inspect the charcoal canister and fuel tank for leaks and damages
  • Check that the purge valve (solenoid) has no leaks

Read more

P0442 Evaporative Emission Control System Leak Detected (small leak)

The code P0442 indicates that the PCM has detected a very small vapor leak somewhere in the EVAP control system

Main Symptoms:

  • Check Engine Light may come on
  • Reduced fuel economy

Possible Causes:

  • Loose or damaged EVAP hoses
  • Defective purge valve
  • The gas cap is loose, missing, or damaged
  • The charcoal canister is leaking
  • The fuel tank is leaking

Diagnostic Steps:

  • Inspect gas cap to see if it’s installed tightly
  • Check for disconnected or cracked EVAP hoses
  • Inspect the charcoal canister and fuel tank for leaks and damages
  • Check that the purge valve (solenoid) has no leaks
  • If the above doesn’t narrow down the problem, perform a smoke test

Read more

P0443 Evaporative Emission Control System Purge Control Valve circuit Malfunction

This code means that either there’s an open in the purge control valve circuit or the circuit has an abnormal voltage (too high or too low)

Main Symptoms:

  • Check Engine Light may come on
  • Car may have a lean condition

Possible Causes:

  • Purge solenoid has short or open
  • Short or open somewhere in the wiring harness to purge valve
  • Driver circuit in PCM has an open or short
  • Water intrusion has caused the connector to break or wear out

Diagnostic Steps:

  • Using a scan tool, command purge valve to open. Listen for a clicking sound (one or many times)
  • If it doesn’t click, examine solenoid and connectors for breakages and signs of extreme wearing out
  • Check all the circuits for wiring problems

Read more

P0446 Evaporative Emission Control System Vent Control Circuit Malfunction

The P0446 indicates that the PCM has detected an open or short in the EVAP control circuit or a short to ground circuit

Main Symptoms: 

  • Check Engine Light comes on

Possible Causes:

  • Defective EVAP vent valve
  • Blockage in vent valve
  • The vent valve control circuit has an open or short

Diagnostic Steps:

  • Examine all wiring to vent valve
  • If the above checks out, replace the vent valve

Read more

P0449 Evaporative Emission Control System Vent Valve/Solenoid Circuit Malfunction

This code happens when the PCM has detected a problem in the circuit that controls the EVAP system vent.

Main Symptoms: 

  • Check Engine Light comes on

Possible Causes:

  • Defective EVAP vent valve
  • Wiring issue in the EVAP vent valve
  • Circuit issue in the EVAP vent valve

Diagnostic Steps:

  • Check all wires leading to the vent valve for shorts and opens
  • Check fuses that power the vent solenoid (in case there are any)
  • Examine if the vent valve has cracks or openings
  • Using a bidirectional scanner, actuate the valve to see if it’s working

Read more

P0452 Evaporative Emission System Pressure Sensor/Switch Low

The P0452 code indicates that the PCM has detected that the fuel tank pressure is abnormally low.

Main Symptoms: 

  • Check Engine Light comes on

Possible Causes:

  • Defective fuel tank pressure (FTP) sensor
  • Wiring problem in the circuits that lead to FTP sensor
  • Broken or cracked vapor line (either to the tank or vacuum canister)
  • Loose gas cap leading to loss of vacuum
  • Leaking gasket in the fuel pump module

Diagnostic Steps:

  • Check vapor hoses for any breakages and opens
  • Since diagnosing this problem is extremely hard (due to the location of the FTP sensor), it’s recommended that you get a professional to do the job

Read more

P0455 Evaporative Emission Control System Leak Detected (large leak)

P0455 code means that PCM has detected a large vapor leak somewhere in the EVAP control system

Main Symptoms:

  • Check Engine Light may come on
  • Reduced fuel economy

Possible Causes:

  • Loose or damaged EVAP hoses
  • The gas cap is loose, missing, or damaged
  • Non-compatible gas cap

Diagnostic Steps:

  • Inspect gas cap to see if it’s installed tightly
  • Check for disconnected or cracked EVAP hoses
  • Inspect the charcoal canister and fuel tank for leaks and damages
  • If the above doesn’t work, replace the gas cap

Read more

P0456 Evaporative Emissions System – Small leak detected

P0456 code means the FTP sensor has detected a small leak in the EVAP system.

Main Symptoms: Check Engine Light comes on

Possible Causes:

  • Faulty gas cap
  • A leak in fuel tank hoses or EVAP hoses
  • A leak in the vent valve or purge valve
  • A leak in the EVAP canister

Diagnostic Steps:

  • Use a bidirectional tool to activate the vent solenoid as you monitor the FTP sensor. It will tell you if the system is sealing properly or not
  • If it is, use a smoke test to determine the leak

Read more

P0457 Evaporative Emission Control System (EVAP) Leak Detected

When there’s a vacuum leak, and the EVAP system can’t draw fuel vapors into the system for efficient burning, the P0457 is triggered.

Main Symptoms:

  • Check Engine Light comes on
  • The smell of fuel in the exhaust
  • Reduced fuel economy

Possible Causes:

  • Check Engine Light comes on
  • The smell of fuel in the exhaust
  • Reduced fuel economy

Diagnostic Steps:

  • Inspect gas cap and check if its loose or has debris that’s preventing it from fitting tightly
  • Inspect vacuum hoses for cracks and breaks
  • Inspect charcoal canister for leaks

Read more

P0463 Evaporative Emission Control System Pressure Sensor High Input

When the fuel level sensor signal is above 5 volts for a prolonged time, P0463 happens.

Main Symptoms:

  • Check Engine Light comes on
  • Fuel light may come on and sound alarm
  • Fluctuating fuel level gauge
  • Fuel level gauge may erroneously read empty or full

Possible Causes:

  • Defective fuel level sensor
  • Problem with fuel level sensor circuit
  • Defective instrument cluster
  • Damaged fuel tank

Diagnostic Steps:

  • Visually inspect fuel tank for damage or leaks
  • Inspect wiring harness
  • Do voltage test on fuel level sensor circuit
  • If all those checkouts, you may have to replace the fuel tank

Read more

P0507 Idle Control System RPM higher Than Expected

The PCM has detected that the engine idle speed is higher than the pre-programmed RPM (typically over 200 RPM)

Main Symptoms:

  • Check Engine Light comes on

Possible Causes:

  • Vacuum leak
  • The defective positive crankcase ventilation valve
  • Leaking air intake
  • Problem with throttle body
  • Defective EVAP system
  • Defective idle air controller (IAC) or a problem with the IAC circuit
  • Failed PCM

Diagnostic Steps:

  • Check for vacuum leaks, damages, and restriction
  • Note that this code is informational more than anything, so look out for other codes that it comes with and address those first

Read more

P0700 Transmission Control System Malfunction

If the transmission control module (TCM) detects a fault in the transmission system and sets a code, the code will be triggered.

Main Symptoms:

  • Check Engine Light comes on
  • Transmission may exhibit problems

Possible Causes: Any transmission-related problem can trigger this code

Diagnostic Steps: This is only an informational code, so pull all transmission codes, address them and do a test drive to fix this code

Read More

Conclusion

“Okay, are you satisfied with this list? Any questions for me?”

Tell me more about the code you have and some problems you are facing in the comment box! I’m willing to reply to you.

1 thought on “OBD2 Codes: Free Download, Lookup, Meaning, Fixes, Full List”

Leave a Comment

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.