P0116
Engine Coolant Temperature Sensor Range/Performance
The coolant temperature sensor reading does not change plausibly during warm-up, or its value disagrees with the intake air temperature when the engine has been off long enough that they should match. Often caused by a sensor that reports near a fixed value despite engine warm-up.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: easy
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
Common causes
Ordered by how often each turns out to be the cause.
- Sensor drifting outside specificationCommon
- Thermostat stuck open (engine never reaches operating temperature)Possible
- Sensor element aged beyond calibration windowLess likely
Parts involved
- Coolant Temperature Sensor
- Thermostat
P0116 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.