Engine Coolant Temperature Sensor Low Input
The ECT signal voltage is below threshold, which the ECU interprets as an implausibly hot coolant temperature (typical NTC sensor characteristic — low resistance at high temperature).
Affected components
- Coolant temperature sensor
- Coolant temperature sensor wiring
Common causes
- High likelihood: Signal wire shorted to ground
- Medium likelihood: Sensor failed shorted internally
Possible symptoms
- Check engine light on
- Cooling fan runs constantly or not at all
- Cabin heater weak or excessively hot
- Possible long warm-up time or hard cold start
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.