OBD-II code · Powertrain (generic)
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.
Is it safe to drive with P0118?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyOpen circuit in sensor or wiring
- PossibleCorroded sensor connector
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
Repair at a glance
- Difficulty
- Easy
- DIY friendly
- Often, with basic tools
- Typical labour
- 0.3–1.5 h
- Emissions test
- Likely to fail
- After the fix
- A drive cycle is needed before the light stays off
- Parts involved
- Coolant Temperature Sensor, Coolant Temperature Sensor Wiring
Related codes
- P0115Engine Coolant Temperature Sensor Circuit Malfunction
- P0116Engine Coolant Temperature Sensor Range/Performance
- P0117Engine Coolant Temperature Sensor Low Input
- P0119Engine Coolant Temperature Sensor Circuit Intermittent
- P011AEngine Coolant Temperature Sensor 1/2 Correlation
- P011BEngine Coolant Temperature/Intake Air Temperature Correlation
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.