P0116Powertrain
Powertrain · SAE
Engine Coolant Temperature Sensor — Range/Performance
Meaning
The engine coolant temperature (ECT) sensor value is outside the plausible range or does not change consistently with engine conditions. The ECU detects a reading inconsistent with run time and ambient temperature.
Common causes
- Faulty or slow ECT sensor
- Thermostat stuck open (engine never warms up)
- Low coolant level or air in the circuit
- Wiring/connector with abnormal resistance
- Sensor not properly in contact with the coolant
Symptoms
- Check engine light on
- Unstable or incorrect temperature reading
- Hard cold start or wrong mixture
- Poorly managed cooling fan
- Increased fuel consumption
Severity
Moderate: a wrong temperature reading degrades mixture and timing, worsening economy and running; should be corrected.
What to do
- Compare cold ECT with ambient temperature (they should match)
- Check how the value behaves during warm-up
- Check thermostat, coolant level and air bleeding
- Measure sensor resistance and inspect the connector