P0117: Engine coolant temperature sensor circuit low

What P0117 means

This sensor’s resistance drops as it heats up, so the hotter the engine, the lower the voltage reaching the ECU. A voltage below what is possible makes it read an absurdly high temperature. It is almost always electrical: a signal wire touching earth or a shorted sensor. Even so, make sure the engine is not really overheating.

Most common causes

• Sensor signal wire chafed and touching earth
• Coolant or moisture inside the connector
• Sensor shorted internally
• Crushed or burnt wiring loom near the engine
• Rarely, the ECU

Symptoms

• Engine warning light on
• Temperature gauge at maximum with the engine not actually hot
• Radiator fan running all the time
• Hard cold starting

Can you drive with P0117?

With care If the engine is not genuinely hot, you can drive with care. But first make sure there is no real overheating (coolant level, leaks, steam): if there is, stop.

How to check it

With the engine cold, a very high coolant temperature reading in live data means an electrical fault. Switch off, unplug the sensor and look again: if the reading drops to a very low value, the wiring is fine and the sensor is shorted.

How to read and clear P0117 with Final OBD

Plug an OBD2 scanner in under the steering wheel, switch the ignition on and open Final OBD. Under Faults you’ll see P0117 with this same explanation and whether it’s confirmed, pending or permanent.

With Free you read this code with its short description for nothing, and clear it if the engine stores it over standard OBD. With Pro you get the full explanation, how the car was running when it was logged (revs, temperature, load) and clearing in every control unit.

Clearing the code only turns the light off: if the cause is still there, it comes back. Clear it once it’s fixed, and not right before the ITV. It’s all in how to read and clear fault codes and in the ITV and OBD.

Similar codes

• P0113 Intake air temperature sensor circuit high
• P0114 Intake air temperature sensor circuit intermittent
• P0115 Engine coolant temperature sensor circuit fault
• P0116 Engine coolant temperature sensor range or performance
• P0118 Engine coolant temperature sensor circuit high
• P0119 Engine coolant temperature sensor circuit intermittent
• P0120 Throttle or pedal position sensor A: circuit fault
• P0121 Throttle or pedal position sensor A: out of expected range
• P0100 Mass or volume air flow sensor circuit fault
• P0101 Air flow sensor range or performance problem
• P0102 Air flow sensor circuit low input
• P0103 Air flow sensor circuit high input

P0117 is a generic code, so it means the same on any make, for example on Citroën, Hyundai, Mercedes-Benz, Mini, Renault, Volvo. See what Final OBD does on your car in makes and models.