P0117: Engine coolant temperature sensor circuit low
The ECU sees a voltage that is too low from the engine temperature sensor, as if it were boiling. Usually a wire shorted to earth or the sensor.
| Code | P0117 |
|---|---|
| System | Engine and transmission |
| Group | P01xx, Air and fuel metering |
| Type | Generic: it means the same on every make |
| Can you keep driving? | With care |
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.
Open the bonnetthe in-depth explanation
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 its description and whether it’s confirmed, pending or permanent.
If the engine stores it over standard OBD, with FREE you read this code with its explanation for nothing and clear it. With PRO you also read the faults of every control unit and clear them in all of them.
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 an inspection. It’s all in how to read and clear fault codes and in inspections 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
- P011A Engine coolant temperature sensors 1 and 2 do not agree
- P011B Engine coolant temperature does not match intake air temperature
- 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
To understand it properly
We explain how that system works, with drawings and no waffle, in our mechanics guide: Cooling.
What does code P0117 mean?
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.
Can you drive with P0117?
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 do you clear P0117?
With an OBD2 scanner and an app like Final OBD, which clears it for free if it’s stored by the engine control unit. But clearing it only turns the light off: if the cause isn’t fixed, P0117 comes back.
Read it on your car
Final OBD reads and clears engine faults through standard OBD for free, each one explained in plain English. With PRO it also reads the faults of every control unit, each make’s own codes included, and clears them in all of them.
