P0116
ECT Sensor Range/Performance
medium
i Description
The Engine Coolant Temperature sensor is not responding as expected during warm-up. The ECU expects the coolant temperature to rise at a predictable rate after a cold start.
? Common Causes
- Stuck-open thermostat
- Faulty ECT sensor
- Low coolant level
- Air pocket in cooling system
- Incorrect thermostat rating
! Symptoms
- Check engine light
- Engine slow to warm up
- Poor heater performance
- Slightly higher fuel consumption
# Diagnostic Steps
- Check thermostat operation (engine should reach operating temp within 5-10 minutes)
- Test ECT sensor resistance
- Check coolant level and bleed air if needed
- Compare ECT reading to infrared thermometer reading on engine
⚙ Typical Fix
Replace the thermostat or ECT sensor.
Parts Needed
Thermostat, ECT sensor, Coolant
Estimated Cost
$50-$250
↔ Related Codes
Q Frequently Asked Questions
Yes, but fuel economy will be worse and the cabin heater may be weak. A stuck-open thermostat is the most common cause and should be replaced.
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