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The power control module (PCM) is an essential part of your vehicle system. For starters, it’s in charge of controlling and monitoring several systems in your engine. But just like any other component, the PCM may also encounter some issues over time.

The P0603 code is an engine trouble code related to an issue with the Internal Control Module Keep Alive Memory (KAM). Read on to learn more about KAM and the P0603 code.

engine control unit
Just like any other component, the PCM may encounter some issues over time.

What Does the P0603 Code Mean?

Diagnostic trouble code (DTC) P0603 stands for “Internal Control Module Keep Alive Memory (KAM) Error.” It is logged once the PCM fails its KAM self-test.  The code is triggered when the result of the self-test calculations are not as expected.

To understand the code better, let’s talk about computer memory and storage. Computers have two types of memory: ROM and RAM.

Read-only memory (ROM) refers to the permanent memory stored in your vehicle’s computer. This data cannot be changed and will remain as it is even if your PCM loses power.

Random-access memory (RAM) refers to the temporary memory that is stored in the PCM. This is where your PCM stores new data. RAM memory can be categorized as volatile or nonvolatile.

Nonvolatile RAM memory will be retained even if you disconnect your car battery. However, data stored in a volatile RAM memory will be lost once you turn off the ignition. Keep alive memory (KAM) is a type of volatile RAM memory that can be wired straight to the battery so that its data won’t be erased when you turn off the ignition.

KAM is crucial because it stores data regarding drive cycles. This memory constantly changes based on driving and sensor inputs. The PCM regularly runs a routine self-check to monitor the performance of the KAM modules. Once the PCM perceives that the results of the mathematical calculations during self-tests are not what’s expected, it will trigger the P0603 code.

Note: The definition of code P0603 may be different depending on the vehicle manufacturer. Consult the appropriate repair manual or repair database for the exact code definition.

Vehicles that are prone to code P0603 include various models of Nissan (especially Nissan Altima), Ford, Infiniti, and Peugeot.

ford engine control module
The PCM regularly runs a routine self-check to monitor the performance of the KAM modules.

What are the Possible Causes of the P0603 Code?

Here are the possible triggers of a P0603 code:

  • Dead battery
  • Wiring and/or connection issues in the PCM’s power or ground circuit
  • PCM software in need of an update
  • Faulty PCM
  • Charging system issues

What are the Common Symptoms of a P0603 Code?

Here are some of the common symptoms related to a P0603 code:

  • Activated check engine light
  • Engine stalling
  • Vehicle won’t start
  • Illuminated ABS or traction control light
  • OBD-II monitor issues
nissan engine control module
P0603 is a generic trouble code, which means it may appear on various makes and models.

How to Diagnose the P0603 Code

Diagnosing a P0603 code isn’t easy. There are several factors that may cause the issue, so it may be hard to identify which component is causing the problem. For instance, you’ll have to identify if it’s caused by a faulty PCM or an issue with the PCM itself. If you don’t have enough experience with auto repair, it’s best to take your vehicle to an auto repair shop and have a mechanic do the diagnostic procedures for you.

However, if you prefer to diagnose this code yourself, we recommend consulting vehicle repair manuals or online repair databases.

How to Fix the P0603 Code

P0603 is a generic trouble code, which means it may appear on various makes and models. However, even if this code is generic, there is no universal solution for all vehicles. For example, repair steps that worked for a P0603 on a Nissan Altima may not work for a P0603 on a Ford F-350.

If you don’t have enough experience and tools to get the job done, we suggest taking your vehicle to an auto repair shop for proper diagnosis and repair. However, if you decide to fix this code yourself, we recommend consulting a vehicle-specific repair manual or subscribing to an online repair database.

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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