P0115 code definition

Engine Coolant Temperature (ECT) sensor circuit malfunction problem

What the P0115 code means

P0115 is the OBD-II generic code that indicates when the engine control module (ECM) reads the ECT sensor input go below or above the sensors expected range of 0.14 to 4.91 V (-40°C to 140°C -40°F to 284°F).

What causes the P0115 code?

The ECT sensor range input to the ECM went to -40°F or above 284°F indicating a short or open circuit.

Codes P0117 or P0118 for a short or open circuit usually accompany code P0115.

What are the symptoms of the P0115 code?

  • The ECM turns on the Check Engine Light and goes into failsafe mode substituting input to 176 degrees F.

  • Engine may have a hard start when engine is cold and start normal when warm

  • Engine may run rough and hesitate until the engine warms up

  • Engine should run close to normal once the engine warms up

Note: The symptoms are determined by the manufacturer failsafe ECM strategy for the vehicle during a failure and may vary between manufacturers and vehicles.

How does a mechanic diagnose the P0115 code?

  • Scans and documents the codes received and view the freeze frame data to see when the code was set

  • Resets the codes to clear the OBD-II fault codes and retests the vehicle to see if the code comes back

If Codes P0117 or P0118 are received, the mechanic follows tests for these codes first.

Common mistakes when diagnosing the P0115 code

  • Not performing a visual inspection first

  • Not performing tests on codes P0117 or P0118 first

  • Not replacing ECT sensor unless tests indicate a problem

  • Not connecting the new ECT sensor and viewing the ECM data to see if the temperature output from the sensor is close to the same as ambient temperature before installation

How serious is the P0115 code?

  • The P0115 code will cause the engine ECM to go into a failsafe mode.

  • The failsafe mode may cause various drive complaints until the engine warms up depending on the manufacturer failsafe mode strategy.

What repairs can fix the P0115 code?

  • Repairing or replacing the ECT connector
  • Repairing or replacing the wiring as necessary
  • Replacing the ECT with a new sensor

Additional comments for consideration regarding the P0115 code

  • The P0115 code is often associated with P0116, P0117, P0118, and P0119 codes.

  • Most failures for code P0115 is a harness shorting or a connector corrosion issue causing an open circuit.

Need help with a P0115 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.

This article originally appeared on YourMechanic.com as P0115 OBD-II Trouble Code: ECT Sensor Circuit Malfunction Problem and was authored by Jay Safford.


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