Check Engine Code
P0118
Engine Coolant Temperature Sensor Circuit High Input
Severity: medium
DIY difficulty: 1/5
Typical cost: $15–$150
What P0118 means
Counterpart to P0117. ECM is seeing an open circuit or implausibly hot coolant reading from the ECT sensor.
Symptoms
- Check engine light
- Cold-start hard / no-start
- Cooling fans running at low temp
- Erratic gauge
Likely causes (most common first)
- Disconnected ECT connector
- Open ECT sensor
- Broken signal wire
- Corroded pins
Can I keep driving?
Medium — drivable but fix soon
Typical repair cost
DIY fixes can start near $15 (parts only). Shop repairs for P0118 typically run up to $150 depending on the underlying cause and vehicle. Start with the most common cause — Disconnected ECT connector — before throwing parts at it.
Related codes
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