Control Module Internal Temperature Sensor A Circuit High
Same as P0666 with the signal voltage above the plausible range. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.
Affected components
- Ecu internal temperature sensor a
Common causes
- High likelihood: Sensor internal open
- Low likelihood: Connector pins corroded - high contact resistance
- Low likelihood: Supply wire pinched against B+ source
Possible symptoms
- Check engine light on
- Possible limp mode or no-start
- Multiple follow-up faults across modules
- Reset/relearn may be needed after repair
Diagnostic notes
- The malfunction indicator lamp may illuminate
Related codes
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.