P0116 Engine Coolant Temperature Circuit Range/Performance

P0116 indicates a range or performance problem in the engine coolant temperature circuit. The coolant temperature signal is not behaving as expected for engine conditions.

Code details

Generic OBD-II · P0

System: Fuel / Air
Code type: Generic (SAE / ISO controlled)
Standard: SAE J2012 / ISO 15031-6

Diagnostic boundary

A diagnostic trouble code reports that a monitored test failed. It does not prove one specific part is bad, and manufacturer logic can add vehicle-specific conditions.

Do not replace the thermostat or sensor based only on one reading; range/performance faults need trend and plausibility checks.

Symptoms of P0116

Check-engine light on, sometimes with rough or uneven running.
Hesitation, surging, or a noticeable change in fuel economy.
Occasionally hard starting or a smell of unburnt fuel.

Common causes of P0116

A failing or contaminated sensor (MAF, MAP, oxygen or air-fuel sensor).
Intake or vacuum leaks, or an exhaust leak near an upstream sensor.
Wiring, connector, or fuel-delivery problems that skew the reading.

Useful checks before replacing parts

Compare coolant temperature to intake-air and ambient temperature after a cold soak.
Watch coolant temperature rise during warm-up and check for sudden jumps, dropouts, or implausible readings.
Inspect coolant level, thermostat behavior, sensor connector condition, wiring, and ground integrity.

Related OBD-II codes

These nearby fuel / air entries can help compare wording and pin down the fault area.