P0603
Internal Control Module Keep Alive Memory (KAM) Error
The ECU detected a fault in its KAM (battery-backed memory used to store adaptations and DTCs). Often appears after battery disconnect or low battery; persistent codes indicate an internal ECU fault.
- Check engine light: Yes
- Emissions related: No
- Repair difficulty: easy
Symptoms
- Check engine light on
- Possible limp mode or no-start
- Multiple follow-up faults across modules
- Reset/relearn may be needed after repair
Common causes
Ordered by how often each turns out to be the cause.
- Battery disconnected or voltage too lowCommon
- ECU internal memory faultLess likely
- Module software outdated, reflash may resolveLess likely
Parts involved
- ECM
- Vehicle Battery
P0603 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.