P0115: Engine coolant temperature sensor circuit fault
The ECU is not getting a valid signal from the engine temperature sensor. Usually the connector, wiring or sensor, and it affects the fan.
| Code | P0115 |
|---|---|
| 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 P0115 means
The coolant temperature sensor tells the ECU how hot the engine is. The ECU uses it to set the fuel mixture and idle speed, decide when to switch on the radiator fan and, on many cars, drive the temperature gauge. This code points to a general fault in its circuit: the signal is missing or makes no sense.
Most common causes
- Loose or corroded sensor connector, or broken pins
- Broken or chafed sensor wire
- A faulty sensor
- A poor earth or reference supply problem
Symptoms
- Engine warning light on
- Temperature gauge not moving or reading oddly
- Radiator fan running all the time
- Hard starting and higher fuel consumption
Can you drive with P0115?
With care You can drive, but without this signal the ECU may not run the fan properly and the engine uses more fuel. Keep an eye on the temperature and get it to a garage soon.
Open the bonnetthe in-depth explanation
How to check it
In live data, compare coolant temperature with the engine cold (it should be close to outside temperature) and after a few minutes running (it should rise steadily). A fixed or absurd value means the sensor or its wiring is at fault.
How to read and clear P0115 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 P0115 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
- P0111 Intake air temperature sensor range or performance
- P0112 Intake air temperature sensor circuit low
- P0113 Intake air temperature sensor circuit high
- P0114 Intake air temperature sensor circuit intermittent
- P0116 Engine coolant temperature sensor range or performance
- P0117 Engine coolant temperature sensor circuit low
- P0118 Engine coolant temperature sensor circuit high
- P0119 Engine coolant temperature sensor circuit intermittent
- 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 P0115 mean?
The coolant temperature sensor tells the ECU how hot the engine is. The ECU uses it to set the fuel mixture and idle speed, decide when to switch on the radiator fan and, on many cars, drive the temperature gauge. This code points to a general fault in its circuit: the signal is missing or makes no sense.
Can you drive with P0115?
You can drive, but without this signal the ECU may not run the fan properly and the engine uses more fuel. Keep an eye on the temperature and get it to a garage soon.
How do you clear P0115?
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, P0115 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.
