P0118: Engine Coolant Temperature Circuit High Input
Can you still drive? You can drive, but the engine will run rich and fuel economy will suffer. The cooling fans may run continuously. Repair soon.
What Does P0118 Mean?
Code P0118 is set when the engine coolant temperature sensor reports an extremely low temperature that is not plausible, which corresponds to a high voltage reading. This usually means the sensor circuit is open or the sensor itself has failed. The ECU may default to a fixed coolant temperature value, affecting fuel mixture and fan operation.
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An OBD-II scanner lets you read and clear diagnostic trouble codes from your vehicle's computer. Most scanners work with any car made after 1996.
Browse OBD-II Scanners on AmazonCommon Causes
- Faulty engine coolant temperature sensor
- Open circuit in ECT sensor wiring
- Corroded ECT sensor connector
- Low coolant level exposing the sensor
Symptoms
- Check engine light on
- Engine running rich
- Poor fuel economy
- Cooling fans running constantly
- Hard starting when engine is warm
Diagnostic Steps
- 1Read and document freeze frame data
- 2Check ECT sensor reading on scan tool compared to actual engine temperature
- 3Inspect ECT sensor connector for corrosion or damage
- 4Test ECT sensor resistance with a multimeter at different temperatures
- 5Check coolant level and condition
- 6Replace ECT sensor if resistance values are out of specification
Recommended Parts & Tools
engine coolant temperature sensor
Estimated Repair Cost
| Type | Estimated Cost |
|---|---|
| Total Repair Cost Range | $20 - $200 |
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Frequently Asked Questions
Why are my cooling fans always on with P0118?
When the ECT sensor reports an implausible reading, the ECU may activate the cooling fans as a safety precaution to prevent potential overheating.
Can low coolant cause P0118?
Yes, if the coolant level drops below the ECT sensor, the sensor cannot read the coolant temperature properly and may trigger P0118.
Community Fix Reports
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