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Powertrain fault code

P0115: Engine Coolant Temperature Sensor 1 Circuit

Fix soon

Usually safe to drive gently to a workshop, but fuel use and running can suffer. Have it checked soon.

What P0115 means

The engine computer is getting a reading from the coolant temperature sensor that is missing, out of range or doesn't make sense. The coolant temperature sensor tells the engine and gauge how hot the engine is.

Common causes

  • Faulty coolant temperature sensor
  • Low coolant level
  • Damaged wiring or connector

What to check first

  1. Scan the car to confirm the code and see if others are stored with it.
  2. Check the sensor plug and wiring for corrosion, damage or a loose connection.
  3. Compare the live sensor reading with a known-good value before replacing the part.

Get P0115 explained for your car: $2.99

  • P0115 explained in full for your make and model: meaning, how urgent, likely causes and what to check, in order.
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  • Your own private report page you can save as a PDF or show your mechanic.

Read your car's codes yourself, free

Plug a cheap ELM327 OBD-II adapter into the port under the dashboard and open the scan tool: Chrome or Edge on a computer with a USB adapter, or Chrome on Android with a Bluetooth LE adapter. It reads and clears codes and shows emissions readiness. It does not work on iPhone.

Open the free scan tool

Need help with P0115?

Tell us your car and what it is doing with P0115. We reply by email with what to check first, in plain words. Free.

Related codes

P0116P0117P0118

General guidance only, not a diagnosis. A qualified mechanic should confirm the cause before you replace parts.