P1604 Toyota Code: Startability Issues And Fixes

Get ready to tackle the P1604 Toyota code with our informative guide. If you’re experiencing engine starting problems, this article is your roadmap to resolution. I’ll walk you through the possible causes, step-by-step diagnosis, and effective solutions for the P1604 code.

Say goodbye to the frustration and hello to a smoothly running vehicle. Let’s dive in and address the P1604 Toyota code together.

P1604 Toyota: A Quick Overview

Here’s a summary of the P1604 for Toyota. Give it a check now!

  • Definition: Startability Malfunction
  • Severity: Medium
  • DIY Skill Level: Intermediate
  • Continue To Drive?: No
  • Estimated Repair Cost: $50 – $500

What Does The P1604 Mean In Toyota Vehicles?

The P1604 diagnostic trouble code (DTC) in Toyota vehicles is defined as “Startability Malfunction” and refers to engine starting trouble or long cranking times. This code is stored when the engine fails to start despite receiving the STA (Start) signal or when it takes an extended period for the engine to start. In addition, the code can be triggered if the engine speed is low or if the engine stalls shortly after starting.

Specifically, the P1604 Toyota code can be triggered if either of the following conditions is met: 

  • 1. The engine speed remains below 500 RPM for a specific duration while the STA signal is active. 


  • 2. The engine speed rapidly drops to 200 RPM or lower within approximately 2 seconds after the engine starts, following an initial speed of 500 RPM or higher.
P1604 Toyota
There are some additional codes commonly going along with the P1604 code, including P1603 and P1605.
(Credit: tacomaworld.com)

The P1604 code commonly occurs in various Toyota models. Some of the models that may experience this code include the Toyota Camry, Corolla, RAV4, Tundra, Camry, and Tacoma.

In some cases, the P1604 DTC may be stored due to engine starting difficulties caused by a fuel shortage. Therefore, checking the fuel level is an important initial step to ensure accurate diagnosis and avoid unnecessary troubleshooting efforts.

Read more: P1605 Toyota Code: Engine Rough Idling Solutions

How Serious Is The P1604 Toyota Code?

The severity level of the P1604 Toyota DTC is considered moderate. While this code indicates engine starting trouble or prolonged cranking times, it does not pose an immediate safety risk or cause significant damage to the vehicle. However, it is not advisable to continue driving with this code present.

When the P1604 DTC is active, the engine may experience difficulties starting, low engine speed, or stalling after starting. This can lead to inconvenience and potential breakdowns, especially in situations where the engine fails to start altogether. To avoid unexpected issues and ensure reliable vehicle operation, it is recommended to address the underlying problem causing the P1604 code immediately.

What Are The Signs Of The P1604 Toyota Code?

The following are common symptoms associated with the P1604 Toyota DTC:

  • Check engine light (MIL) illuminated
  • Engine fails to start
  • Extended cranking time
  • Low engine speed
  • Engine stalls shortly after starting
  • Engine misfire

What Are The Causes Of The P1604 Code In Toyota Vehicles?

The P1604 Toyota DTC can be caused by various factors, including:

  • Immobilizer system malfunction
  • Engine assembly issues such as excess friction or compression loss
  • Faulty starter assembly
  • Malfunctioning crankshaft position sensor and/or camshaft position sensor
  • Malfunctioning engine coolant temperature sensor
  • Issues with fuel system (fuel pump, fuel injector, etc.)
  • Issues with the throttle body or pressure regulator
  • Battery-related problems
  • Faulty drive plate or flywheel
  • Malfunctioning spark plug or ignition coil circuit
  • Problems with the intake system or camshaft timing oil control valve
  • Malfunctioning mass air flow meter or air-fuel ratio sensor
  • Valve timing issues
  • Issues with the purge VSV (Vacuum Switching Valve)
  • Malfunctioning intake valve
  • Problems with the Engine Control Module (ECM)

Please note that further diagnostics may be necessary to pinpoint the exact cause of the P1604 Toyota code.

Read more: Toyota OBD1/OBD2 Codes List [FREE DOWNLOAD]

How To Diagnose And Repair P1604 Toyota Code?

In this section, I’ll talk about the tools and parts you might need, walk you through a guide for diagnosing and resolving the P1604 Toyota code issue, and discuss the level of DIY repair required, along with potential cost estimates.

Though some tasks can be tackled by DIY enthusiasts, it is advisable to seek professional assistance if unsure or when dealing with more complex repairs.

Diagnostic Tools And Essential Parts

To diagnose and repair the P1604 Toyota code, you may need the following tools and parts:

Step-by-Step Guide 

  1. Use an OBD-II scan tool to retrieve and record any additional trouble codes and freeze frame data.
  2. Inspect the battery and electrical connections for any signs of corrosion or damage. Repair any detected problem.
  3. Check the fuel level and ensure the vehicle has an adequate fuel supply. Fill the tank if the fuel level is low.
  4. Test the fuel pressure using a fuel pressure gauge to ensure it meets manufacturer specifications. Make any modifications if needed.
  5. Inspect the spark plugs for wear, fouling, or damage and replace if necessary.
  6. Use a multimeter to test the crankshaft position sensor and camshaft position sensor for proper operation. Repair or replace the parts if problems occur.
  7. Check the engine coolant temperature sensor for any faults or inconsistencies.
  8. Inspect the wiring and connections related to the starting system and repair any damaged or loose connections.
  9. Perform a thorough inspection of the intake system, including the throttle body and intake valve, for any obstructions or malfunctioning components. Repair or replace if necessary.


  • This guide may not address all possible causes, and if the code reappears or persists, we highly recommend seeking the assistance of a skilled mechanic.
  • It is important to record the freeze frame data. This data is helpful in determining the underlying cause of the code. Consult this TSB for more details.

DIY Repair Level And Estimated Costs

The diagnostic procedure for the P1604 Toyota code requires intermediate-level automotive repair knowledge and experience.

While DIY enthusiasts can perform some steps, such as checking electrical connections and inspecting spark plugs, other tasks may necessitate specialized tools or expertise. We recommend consulting a professional mechanic for a comprehensive diagnosis and repair.

The estimated costs for repairing the P1604 code can vary depending on the specific cause and the necessary repairs. Here is a general cost breakdown:

Repair TaskEstimated Cost
Replacement of spark plugs$40 – $100
Repairing wiring/connectors$50 – $200
Replacement of sensors$100 – $300
Fuel system repairs$100 – $500
Other component repairsVaries


Resolving the P1604 Toyota code and getting your vehicle back on track is within your reach. Furthermore, with the knowledge and steps provided, you can confidently diagnose and address this issue. Don’t keep this valuable information to yourself – share it with fellow Toyota owners who may be encountering the same challenge.

Remember, if the P1604 code reappears or persists, it’s advisable to seek the expertise of a skilled mechanic for an accurate diagnosis and precise repairs.

If you have any questions or success stories, we’re here to listen. Share your experiences and insights in the comments section below. Let’s engage in a discussion and support each other!

Reference Sources

  1. JustAnswer, P1604 Startability Malfunction
  2. RepairSmith, 10 Prominent Weak Car Battery Symptoms

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