P1115moderate severityPowertrain
ECT Sensor Circuit Intermittent High Voltage
on 2005 Buick Century 3.1L V6 · FWD
What this code means
The PCM detected intermittent high voltage on the Engine Coolant Temperature sensor circuit, indicating the sensor is sporadically reporting very low temperatures.
Symptoms
- Check Engine Light
- Rich running condition
- Poor fuel economy
- Cooling fans not activating when needed
Common causes
- Intermittent open in ECT circuit
- Loose ECT connector
- Faulty ECT sensor
- Corroded terminals
Diagnostic steps
- Monitor ECT readings for erratic spikes
- Wiggle test ECT connector
- Test sensor resistance across temperature range
- Check connector terminals
Repair notes
Clean and secure ECT connector. Replace sensor if faulty.
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