P0606
ECM/PCM Processor Fault
What it means
The Engine Control Module has detected an internal processor fault — its own self-test has failed. Almost always indicates the ECM is failing or already failed.
Common causes
Listed in rough order of frequency. Verify with vehicle-specific service info before parts replacement.
- 01Internal ECM hardware failure (capacitor / processor)
- 02Water damage to the ECM
- 03Recent jump-start or battery surge damage
- 04Failed ECM ground or power supply
- 05Corrupted ECM firmware (rare — usually after a botched flash)
Affected systems
ECUs and subsystems that report or are affected by this code.
Related ECU variants we cover
P0606 commonly appears on these variants in our patch catalog. Each links to the full coverage detail.
Get vehicle-specific diagnosis for P0606
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Ask the forums about P0606Critical-severity code
This code typically prevents the vehicle from starting, running normally, or operating safely. Diagnose carefully before clearing — clearing without fixing the root cause often masks deeper problems.