P0118 – Engine Coolant Temperature Circuit High Input
Description
The ECM detects an abnormally high voltage from the ECT sensor, usually caused by an open circuit or sensor failure.
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View Recommended ScannersSymptoms
- Check engine light
- Poor fuel economy
- Hard starting
- Cooling fans always on
- High idle
Causes
- Open circuit in ECT wiring
- Faulty ECT sensor
- Corroded connector
- Low coolant
- ECM fault
Diagnosis
- Monitor ECT voltage
- Inspect wiring for opens
- Check coolant level
- Compare sensor reading to actual temp
Repair
- Replace ECT sensor
- Repair wiring
- Fix connector
- Refill coolant
- Replace ECM if required
