P0603: Internal Control Module Keep Alive Memory (KAM) Error
P0603 means Internal Control Module Keep Alive Memory (KAM) Error. The memory the engine computer keeps while the ignition is off (learned values) has been lost or corrupted. Battery disconnection or a power interruption is a common cause.
Can I keep driving? Limit driving and diagnose promptly. Continued driving can cause damage, stalling or limp mode.
Common symptoms
- Check engine light on
- Possible stalling, no-start or limp mode
- Other modules may report communication errors
Possible causes
- Low or unstable battery voltage
- Poor control module ground or power supply
- Interrupted or incorrect software programming
- Internal control module failure
- Water damage
How to diagnose P0603
- Check battery condition and charging voltage first.
- Check control module power and ground circuits.
- Check for available software updates from the manufacturer.
- Ask whether the module was recently reprogrammed or tuned.
- A replacement module usually needs to be programmed to the vehicle.
What the code means, digit by digit
Generic codes have the same definition on every OBD-II vehicle (petrol cars from model year 1996 in the US, 2001 in the EU; diesels later). Manufacturers can add their own enhanced codes; those are not listed here.
Related codes
General guidance only. Fault codes describe what the engine computer saw, not which part failed: confirm with testing before replacing parts, and follow the vehicle's service information.