P0117: Engine Coolant Temperature Sensor Circuit Low Input
Can you still drive? Use caution. First verify the engine is not actually overheating by checking the coolant level. If coolant is full and the engine feels normal, the sensor is likely faulty.
What Does P0117 Mean?
Code P0117 indicates that the engine coolant temperature sensor is reporting an abnormally low voltage, corresponding to an extremely high temperature reading. This could mean the sensor has failed, there is a short in the wiring, or in rare cases the engine is actually severely overheating. The ECM uses coolant temperature to adjust fuel delivery, idle speed, and cooling fan operation.
Need to read your codes?
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
- Shorted coolant temperature sensor
- Wiring short to ground
- Corroded connector pins
- Damaged wiring insulation contacting engine ground
- Actually overheating engine
Symptoms
- Check engine light on
- Cooling fans running constantly
- Rich running condition
- Poor fuel economy
- Inaccurate temperature gauge reading
Diagnostic Steps
- 1Verify actual engine temperature with infrared thermometer
- 2Check coolant level to rule out actual overheating
- 3Measure sensor resistance and compare to specifications
- 4Disconnect sensor and check if reading changes to maximum
- 5Inspect wiring for shorts to ground
- 6Check connector for coolant contamination or corrosion
Recommended Parts & Tools
engine coolant temperature sensor
electrical connector cleaner
Estimated Repair Cost
| Type | Estimated Cost |
|---|---|
| Total Repair Cost Range | $25 - $250 |
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Chat with AI About P0117Commonly Affected Vehicles
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Frequently Asked Questions
How do I know if my engine is really overheating?
Check the coolant level, feel the upper radiator hose (it should be hot but not impossible to touch), and use an infrared thermometer on the thermostat housing. Normal operating temp is 195-220 degrees F.
Why are my cooling fans running all the time?
With P0117, the ECM thinks the engine is extremely hot and commands the fans to run continuously as a safety measure. Replacing the faulty sensor will fix this.
Community Fix Reports
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