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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 at a glance
CodeP0115
SystemEngine and transmission
GroupP01xx, Air and fuel metering
TypeGeneric: 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.

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 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

P0115 is a generic code, so it means the same on any make, for example on BMW, Ford, Mercedes-Benz, Peugeot, Renault, Volkswagen. See what Final OBD does on your car in makes and models.

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.