P0102 – Mass or volume air flow “A” circuit low

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The P0102 code tells you there’s a problem with the mass air flow sensor in your engine. This component is crucial to maintaining the correct air to fuel ratio in your engine. While the P0102 trouble code isn’t serious on its own, ignoring it could lead to further engine damage.

Activation of the P0102 OBD2 code doesn’t always mean your mass air flow sensor is failing. There are other components that may be causing the problem. Read on below to learn the correct steps for diagnosing and repairing this issue.

P0102 code definition

P0102 code definition (generic): Mass or volume air flow circuit low

P0102 BMW code definition: Mass or volume air flow circuit low input

P0102 Ford code definition: Mass or volume air flow circuit low input

P0102 GM code definition: Mass or volume air flow circuit low input

P0102 Hyundai code definition: Mass or volume air flow circuit low input

P0102 Nissan code definition: Mass or volume air flow circuit low input

P0102 Subaru code definition: Mass or volume air flow circuit low input

P0102 Toyota code definition: Mass or volume air flow circuit low input

Here's where you can get a thorough understanding of the P0102 OBD2 code
If you want to learn about the P0102 OBD2 code, this is the right place

What does P0102 mean?

The amount of air that comes into the engine is measured by the mass air flow (MAF) sensor. This data is used to maintain the correct air-to-fuel mixture, which is important for making sure the cylinders fire correctly. 

The P0102 code is a general code related to the MAF sensor. It indicates the voltage output to the engine control module (ECM) or powertrain control module (PCM) is too low. This means the sensor isn’t performing within its usual parameters, and the data it generates could be faulty.

You can find the MAF sensor downstream of the air filter on the engine air intake system. To get a more specific location, check your vehicle’s manual. Your manual should also tell you whether your MAF sensor includes an air temperature sensor, which some vehicles use to give more complete data.

It’s common to see other diagnostic trouble codes along with P0102. These include P0101, P0103, and P0104, all of which are also related to the MAF sensor.

What are the symptoms of the P0102 code?

It’s likely your engine will run normally most of the time, with erratic or sporadic drivability issues. The most common symptoms of the P0102 code include:

  • Activation of the check engine light,
  • Black smoke in the exhaust,
  • Inconsistent or rough idle,
  • Reduced fuel consumption, resulting in air/fuel mixture that’s too lean,
  • Reduced engine power,
  • Hard starts and stalls.
A problem with the MAF sensor can be indicated by the P0102 code
The P0102 code tells you there’s a problem with the mass air flow sensor

What are the causes of P0102?

  • Faulty MAF sensor,
  • Dirty MAF sensor or air filter,
  • Failed or disconnected wiring around the MAF sensor electrical harness,
  • Damage or corrosion on MAF terminals,
  • Leaks in the air intake or exhaust system,
  • Clogged passages or hoses in the air intake or exhaust system,
  • Faulty electrical system (rare.)

How serious is the P0102 code?

The P0102 code is of relatively low severity. In some cases, you won’t even experience any drivability symptoms. Those that do occur are generally mild and don’t pose a danger to the driver or the engine. While you should fix the problem as soon as possible, you can safely drive your car until you do.

How to diagnose the P0102 code

Tools you’ll need:

The P0102 code can be diagnosed with an OBD2 scan tool
An OBD2 scan tool can be used to diagnose the P0102 code


  1. Check if there are any technical service bulletins available for your vehicle’s make and model. There may be a known issue for your vehicle that can save you the diagnostic work.
  2. Scan your system for other OBD2 codes. Other trouble codes related to the MAF sensor could help you identify the source of the problem. 
  3. Clear the codes and take a test drive while reading the live data on your OBD2 scanner. Pay attention to the readings from both the MAF sensor and the oxygen sensors.
  4. Check the wiring and connections around the MAF sensor. Replace any that are frayed or damaged, then make sure they’re securely fastened and not installed too closely to other engine components.
  5. Inspect the hoses of the air intake system for leaks. Pay special attention to the ends, and feel along any hidden spots for wear or damage.  
  6. Check the air filter. Replace it if it’s clogged or dirty.
  7. Test if your MAF sensor is operating. Let your car sit overnight, then start it and carefully disconnect the electrical harness. The engine should shut off. If it doesn’t, your MAF sensor is faulty. 
  8. Remove the MAF sensor and visually inspect it for dirt or corrosion. If you see any, clean it with a spray-on MAF sensor cleaner, carefully re-install it, and ensure all connections are secure. 
  9. Use a digital multimeter to test the wiring around the MAF circuit. Replace any that don’t read the correct voltage stated in your vehicle’s manual. 

Common mistakes to avoid while diagnosing the P0102 code

Many people assume the MAF sensor has failed without taking the time to inspect it for build-up and corrosion. Even if you’ve identified the sensor as the problem, it may simply need to be cleaned, not replaced. 

If you do need to replace your MAF sensor, make sure you use an original equipment (OEM) component. Aftermarket products may not be compatible with your system, which can lead to further problems. 

What should you do to fix the code P0102?

After each step of the repair, clear the codes using an OBD2 scan tool and test drive your vehicle to see if they recurs. This will prevent you from making unnecessary repairs.

  1. Replace any damaged or faulty wires found during your diagnosis.
  2. Replace the MAF sensor if it still fails the diagnosis after cleaning. 
  3. Small holes in your air intake system may not be visible to the naked eye, but could still cause a vacuum leak. A smoke test can help you find these hidden leaks. You can rent smoke machines from many auto parts stores. Conduct a test using the “visible smoke” setting, then replace any leaking components.
  4. If P0102 comes back, you may have a more serious electrical problem. Take your vehicle to a mechanic for further diagnosis.
How to fix the P0102 trouble code

Tips to avoid P0102 in the future

Faulty wiring is the number one culprit when it comes to the P0102 code. Make sure to keep all wires away from components that could damage them, especially parts that reach high temperatures. You can also treat your engine with anti-corrosion compounds to help stave off damage.

Read more:

P1101 Chevy Cruze – Intake Air Flow System Performance

P0101 Code: Meaning, Symptoms, Causes, Diagnostics, and Fixes