Engine Coolant Temperature Sensor 3 Circuit Intermittent/Erratic
Intermittent signal from ECT sensor 3. The engine coolant temperature sensor feeds warm-up enrichment, fan control and closed-loop entry — a stuck-cold reading keeps the engine in open loop and rich forever.
Affected components
- Ect sensor 3
- Sensor wiring
Common causes
- High likelihood: Connector loose or corroded
- Low likelihood: Connector with intermittent contact under vibration
- Low likelihood: Harness routed against vibrating component
Possible 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
Diagnostic notes
- The malfunction indicator lamp may illuminate
- This code can affect emissions
- A drive cycle may be required after repair
Related codes
Sources
Diagnostic information is provided for reference only. Confirm the code with a compatible scan tool and follow the vehicle manufacturer's service procedures before replacing components.