P0603 Code: Meaning, Causes, Symptoms, & How to Fix It

P0603 Code

If you are a car owner, you’re probably familiar with the anxiety of receiving an engine code. Having a check engine light show up on your dashboard can be an unsettling experience. One such code that may pop up is P0603, which typically indicates a problem with the computer’s internal memory.

If the code P0603 is triggered, you may find yourself unsure of how to proceed. This article will provide an detailed overview of the causes, symptoms, and steps you can take to identify and fix this code. It’s important to understand that the severity of this code varies greatly, so it’s best to take a systematic approach when diagnosing possible solutions.

P0603 Code Meaning

If you’re seeing the P0603 code on your car’s diagnostic system, it means that your vehicle’s Powertrain Control Module (PCM) has detected an unexpected error in its Keep Alive Memory. This code indicates that the PCM has failed in its Keep Alive Memory (KAM) self-test. This means the drive cycle storage information isn’t properly being communicated with the engine control module, which can lead to a variety of issues.

The P0603 means Internal Control Module Keep Alive Memory (KAM) Error. It is a generic trouble code that comes up when the Powertrain Control Module (PCM) has been able to detect a problem with the Keep Alive Memory. 

If you do not know the Keep Alive Memory (KAM), it is a type of memory integrated circuit chip used in powertrain control modules (PCMs) in cars. It remains powered even when the ignition is switched off, receiving power from the car battery. KAM works similarly to RAM by storing information about vehicle operating conditions that the PCM uses to adjust aspects of vehicle performance to your specific driving needs. This includes idle speed, fuel trim, and refueling events. When you replace the vehicle’s battery, KAM will remember the drive cycles and adaptive learning contents it has stored so that you can continue to experience optimum vehicle performance.

The PCM tests the vehicle’s parts to ensure they are functioning properly. One of the functions of the KAM is to store the results of the tests. The code will get thrown when the self-test fails. Furthermore, the trouble code P0603 shows that there might be an issue with either the PCM, KAM, or the battery. 

Causes Of The P0603 Trouble Code

The error code’s primary cause is usually related to the PCM or the battery. They are responsible for the proper diagnostics test carried out periodically and also ensure that the KAM stays active. When they get faulty, the code is most likely to come up. Below are some of the common causes of the P0603 code.

  1. Issue With The Battery
  2. Faulty PCM 
  3. Software Issue 
  4. Faulty Circuit

1. Issue With The Battery

Corroded Battery Terminal with Blue Salt
Corroded Battery Terminal with Blue Salt

The battery plays an essential role in powering the PCM and the KAM. When the battery gets weak and cannot correctly power this component, when this happens, the PCM will not be able to have a complete and successful test of the appropriate part of the vehicle. It then leaves a record in the KAM of a failed test. 

2. Faulty PCM 


The PCM is the part of the vehicle that initiates that self-diagnostic test. When the PCM is faulty, the test will not occur; if it does, it might not be successful. A defective PCM will also come with numerous other codes, and this is because it is responsible for ensuring that the engine and other essential parts of the vehicle work perfectly. 

3. Software Issue 

Still relating to the PCM, the error code could result from a defaulting software in the PCM, and by updating the software, the error code could stop coming up. 

4. Faulty Circuit

Another cause of the error is a bad circuit that supplies inadequate power to the PCM. The P0603 error can also be attributed to a lack of adequate power delivery through an insufficient power or ground connection. It is caused by various aspects not limited to a faulty battery or battery terminal alone, the circuit responsible for the PCM. A faulty wiring could cause the PCM not to get the required electrical voltage. This inadequate power supply disrupts the flow of energy to the component, leading to an interruption in its normal operation.

Symptoms Of The P0603 Code

You will notice these common symptoms when the trouble code comes up. It is easy to mistake the symptoms for a failing transmission system. If your vehicle throws the P0603 code, it is bound to show some symptoms, including the following. 

  • Loss Of Engine Power 
  • Engine Misfire 
  • Engine Lights Triggered 
  • Rough Idle 
  • Difficulty In Starting The Engine 
  • Bad Gear Shift 
  • Bad Fuel Mileage

Can You Drive With A P0603 Code

The P0603 code is a serious issue, and when noticed, it is advisable to park your vehicle and fix the problems first. All the symptoms your car will have come from this code result from the KAM. It cannot record the performances of these parts and its setting, which could alter how they function. 

With this problem code, the vehicle will continuously create an issue until the source of the code is resolved.

How To Fix P0603 Code

Fixing Car Issue
Fixing Car Issue
  • When repairing the trouble code P0603, you first have to run a diagnosis to determine the location of the problem. As we know, the significant parts of the vehicle that could cause the code to come up are the battery and PCM. Other minor causes could be a result of the wiring. 
  • To properly diagnose the cause of the trouble code, you should inspect these parts physically. You can start with the battery, inspect the battery and check the terminals for rust. Also, ensure that the battery is functioning well. If something is wrong with the battery, you may need to replace it as soon as possible. Also, inspect the wiring of the battery and ensure that they are not burnt or disconnected; if they are, get them replaced. 
  • Another part of the vehicle that needs checking is the PCM. If you suspect that there is not enough electric current going into the PCM, you can get the wiring harness checked. Trace the wires from the PCM to the fuse box or wherever it ends. Get the wiring harness changed as soon as possible if you notice any corrosion, burn, or disconnection. Examine the circuit and see if it is faulty or if there has been a short circuit, and replace any damaged part that you notice. 
  • However, if the problem is not with the wiring connection but with the PCM itself, it will either need a replacement or software update, depending on what is wrong with the PCM. You can also diagnose the causes of the code using an OBD scan tool. All you need to do is connect the scan tool to the vehicle, search for related code, and solve the problems. 

Final Thought!

The P0603 is a generic trouble code that has to do with the Keep Alive Memory (KAM). The code will come up when there is a problem in the self-test procedure, and the KAM records the failed test. Have the related parts to the trouble code tested and fixed immediately when the code comes up.  

Sign Up

    About The Author

    Leave a Comment

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

    Scroll to Top