P0606Powertrain
Powertrain · SAE
Engine Control Module (ECM/PCM) — Processor Fault
Meaning
The ECU detects an internal fault in its own processor or memory during self-test. This is a fault of the control module itself, not of an external sensor.
Common causes
- Internal ECU fault (processor/memory)
- Unstable ECU power supply or ground
- Corroded or loose supply wiring
- Failed or corrupted software update (flash)
- Moisture or overvoltage damage in the module
Symptoms
- Check engine light on
- Erratic running or limp/recovery mode
- Sudden stalling or no-start
- Erratic response of engine controls
Severity
Serious: an ECU fault can strand the vehicle or cause unpredictable behaviour; address it immediately.
What to do
- Carefully check ECU power supplies and grounds
- Inspect connectors for corrosion and loose contacts
- Reflash/update the software if the maker provides it
- Replace or recondition the ECU if the internal fault is confirmed