P0603Medium urgency
Internal Control Module Keep Alive Memory (KAM) Error
Network · ECM/PCM
⚠️ The ECU has lost its learned calibrations. Expect rough idle and poor fuel trims until the ECU re-learns over 50–100 miles of driving.
What this means
The ECU's Keep Alive Memory — where learned values like fuel trims and idle calibrations are stored — has experienced an error or been corrupted.
Likely causes
- Battery disconnection or dead batteryMost common
- ECU power supply interruptionMost common
- Failed ECU memory chipLess common
Estimated repair cost
Battery replacement (if battery failed)$130 – $250
ECU inspection and reprogramming$100 – $400
ECU replacement$500 – $2,000
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Frequently asked questions about P0603
What does P0603 mean?
The ECU's Keep Alive Memory — where learned values like fuel trims and idle calibrations are stored — has experienced an error or been corrupted.
Is P0603 serious?
The ECU has lost its learned calibrations. Expect rough idle and poor fuel trims until the ECU re-learns over 50–100 miles of driving.
How much does it cost to fix P0603?
Repair costs for P0603 range from $130 – $250 depending on the root cause and your vehicle.
Can I drive with P0603?
You can drive short distances but should have it repaired within 1–2 weeks to prevent further damage.