CarSense › Trouble codes › P0603

P0603: Internal Control Module Keep Alive Memory (KAM) Error

What this check-engine code means in plain English, what usually causes it, and what a fix typically costs.

Severity: Urgent — can cause stalling, no-start, or unsafe operation

What P0603 means

The powertrain control module (PCM) has detected an internal memory error in its Keep Alive Memory (KAM), which stores critical learned data like fuel trims and idle settings. This indicates the computer itself is malfunctioning or has lost power unexpectedly, and it may not be able to control the engine properly.

What causes P0603?

Likely
Low or failing batteryA weak battery or poor connections can cause voltage drops that corrupt the PCM's memory.
Likely
Faulty PCM/ECMThe engine control module itself may have internal hardware failure or corrupted memory chips.
Possible
Corroded or loose battery cablesPoor electrical connections can interrupt power to the PCM and cause memory errors.
Possible
Recent battery disconnect or jump-startAbrupt power loss or voltage spikes during service can trigger temporary memory faults.

Is P0603 safe to drive?

Drive it?
Not recommended
Watch for
Stalling, rough idle, no-start, erratic shifting
DIY-friendly?
Check battery and connections; clearing the code may help if caused by a one-time event

Driving is not recommended because the PCM may not control the engine or transmission reliably. The vehicle may stall unexpectedly, fail to start, or exhibit dangerous driveability issues. If you must drive, keep trips very short and stay off highways until diagnosed.

P0603 repair cost

~$100 – $1200+

Industry-average estimates. Cost depends on whether it's a simple battery/connection issue or requires PCM replacement and reprogramming.

Which one is it for your car?

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