ECM/PCM Internal Engine Off Timer Performance
The engine controller's internal soak-time/engine-off timer fails its plausibility check — for example readings claim instant cool-down or never-cooled. Cold-start enrichment, EVAP and catalyst monitors depend on this timer; a fault freezes those readiness monitors.
Affected components
- Ecm
Common causes
- High likelihood: ECU internal timer fault
- Medium likelihood: Keep-alive memory power intermittent
Diagnostic notes
- The malfunction indicator lamp may illuminate
- This code can affect emissions
- A drive cycle may be required after repair
Sources
Diagnostic information is provided for reference only. Confirm the code with a compatible scan tool and follow the vehicle manufacturer's service procedures before replacing components.