P0603 – Engine control module (ECM) -KAM error

By Justin DeSantis (Contact Me)
Last Updated 2016-11-11
I have over 20 years experience working on anything with an engine.

Table of Contents

1. What Does Code P0603 Mean?
2. What are the common causes of code P0603 ?
3. What are the symptoms of code P0603 ?
4. How do you troubleshoot code P0603 ?
5. Codes Related to P0603
6. Get Help with P0603

What Does Code P0603 Mean?

The engine control module in your car is a sophisticated computer responsible for controlling all the electronics concerned with vehicle operation. In addition to simply controlling things like ignition timing and fuel mix, on many modern vehicles, it also store information as you drive. It “learns” how you drive and can suit vehicle performance to match your specific needs and common conditions. This is referred to as the “Keep Alive Memory”, or KAM. When the P0603 error is present the ECM is operating on it’s default parameters rather than the information stored via drive cycles.

Note: It’s very common to see this code on vehicles, especially diesel trucks, when the owners have installed aftermarket engine management products. In these cases, the code can’t be repaired or cleared unless the aftermarket products are removed.

What are the common causes of code P0603 ?

• Aftermarket tuning products are a very common cause
• Faulty wiring related to the ECM
• Water intrusion of the ECM
• Faulty wiring of the ignition system allowing interference
• Faulty ECM

What are the symptoms of code P0603 ?

• The check engine light is the first and often the only indicator of a KAM issue
• Since the ECM is involved, other warning lights may also illuminate
• Engine stalling
• Intermittent engine stumble
• Rough idle
• Increased fuel consumption

How do you troubleshoot code P0603 ?

P0603 KAM codes can be difficult to diagnose. Before beginning diagnosis, make sure the battery is fully charged so any measurements taken will be accurate. Inspect the battery cables. A corroded or loose cable can cause the error. Pay special attention to where the cables attach to the battery terminals, and where the ground cable attatches to the chassis. Also look at the wiring harness going into the fuse box, make sure the wires and insulation are in good condition.

Locate the ECM and carefully inspect it and all wiring around it. Most vehicles require 12.5 volts supplied to the ECM. Using the model specific wiring diagram, located in the service manual, find the power supply wire and measure voltage. If it reads 12.5 volts, try flexing the wiring harness and moving it, if voltage changes, that indicates a loose or broken wire. Look for signs of water intrusion. If water enters the ECM, it can have unpredictable results. Inspect the sparkplug wires, and caps, look for cracks or any signs of ignition voltage being able to “leak” out. The high voltage of the ignition system can cause electrical interference if it’s not fully insulated. Any faulty wiring should be repaired or replaced before diagnosis can be complete. A very small defect in wiring can cause error codes, so be diligent in inspection.

If there are no other symptoms besides the P0603 error code, and no visibly defective wiring, the ECM itself can be suspected. In some cases, ECM software is updated by the manufacturer and having it reflashed by the dealer will clear the code and solve the problem. Since this software is only distributed to dealerships, the only way to have this done is to take your vehicle to the dealership.

Codes Related to P0603

P0603 is a memory code from the ECU and often appears on it’s own with no other codes present. If the ECU is faulty, you may see other memory related codes as well, they are:

• P0600- Serial Communication error
• P0601- Internal Control Module Memory Check Sum error
• P0602- ECM Programming error
• P0604- Internal Control module Random Access Memory (RAM) Error
• P0605- Internal Control Module Read Memory (ROM) Failure
• P0606- ECM/PCM Processor error
• P0607- Control Module Performance error

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