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Much like your home computer, your car’s powertrain control module (PCM) has two primary types of memory. The first is permanent, which is the read-only memory (ROM); the second one is temporary and is known as the random access memory (RAM).

If the PCM detects a problem with the RAM portion of its internal memory, it may log the P0604 code.

What Does the P0604 Code Mean?

Diagnostic trouble code (DTC) stands for “Internal Control Module Random Access Memory (RAM) Error.” It warns about an internal problem with the PCM’s random access memory (RAM) that stores its Keep Alive Memory (KAM) strategies.

car PCM
Code P0604 warns about an internal problem with the PCM’s random access memory (RAM) that stores its Keep Alive Memory (KAM) strategies.

The PCM relies on adaptive strategies when calculating important functions, such as fuel delivery and automatic transmission operation. It stores the most important data in dedicated KAM memory that keeps the calculations “alive” even after turning off the engine.

To ensure its ability to operate as designed, the PCM regularly runs internal self-tests on both the ROM and RAM portions of memory. If an issue is detected with the RAM function, code P0604 is set.

Note: The Society of Automotive Engineers (SAE) set the generic code P0604. The vehicle’s manufacturer may have programmed a different definition for this code. Check the appropriate repair manual.

Vehicles that are prone to code p0604 include various models of Chevrolet (especially Chevy Impala), Ford, BMW, Pontiac, and Kia.

What are the Possible Causes of the P0604 Code?

Possible reasons for the PCM logging an internal control module RAM error code include:

  • A faulty PCM
  • PCM software in need of reprogramming

What are the Common Symptoms of the P0604 Code?

The KAM calculations govern various engine systems and processes. A problem with the RAM modules that store these settings can trigger these warning signs associated with an error code P0604:

  • Check Engine Light
  • OBD-II Monitor system issues cause vehicle to fail emission tests
  • Anti-Brake Lock System/Traction Control Light activates
  • Problems with engine operation and shifting transmission gears
  • Vehicle will not start

The P0604 code can sometimes affect the vehicle’s performance, causing issues like the engine seemingly misfiring or even dying once the vehicle stops. In rare cases, you may not notice any symptom at all.

car abs system
Your ABS Light could activate if your PCM is running code P0604.

How to Diagnose the P0604 Code

Fixing an internal control module RAM error code in your car’s PCM can challenge even the most skilled mechanic or technician. Unless you have absolute confidence in your DIY auto repair skills, it’s best to bring your vehicle to a shop.

For those who plan to diagnose the P0604 code in their vehicle, consult a repair manual and other appropriate sources of repair information.

How to Fix the P0604 Code

Like other trouble codes, the P0604 code has no universal resolution. The appropriate repair will vary depending on what triggered the code, and in some cases, your vehicle’s make and model.

Once you’ve determined what set the P0604 code, research ways to resolve it that are specific to your car. You can use auto repair resources and guides.

To get access to comprehensive factory repair information, consider securing an ALLDATA subscription. It’ll help you resolve not only the P0604 code but also any other issue that your car may experience in the future.

Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic.

File Under : OBD-II Trouble Codes Tagged With :
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