Powertrain
generic / SAE
P0118
Engine Coolant Temperature Sensor High Input
The ECT signal voltage is above threshold, which the ECU interprets as an implausibly cold temperature (open-circuit-like behaviour). When this code is active, the ECU runs a default cold-start enrichment that wastes fuel and may cause black smoke.
SystemPowertrain
Typegeneric / SAE
GroupP0
Range / number1 / 18
Possible causes
- Open circuit in sensor or wiring high
- Corroded sensor connector medium
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
Inspection / repair
- Difficulty: easy
- DIY: possible
- Estimated cost: 30–200 €
- Estimated time: 0.3–1.5 h
- Component: coolant temperature sensor
- Component: coolant temperature sensor wiring
- MIL / check engine light
- emissions-relevant
- drive cycle required
Sources
References
sae:J2012