Circuit Description

A thermistor built into the engine coolant temperature (ECT) sensor changes the resistance value according to the engine coolant temperature. The structure of the sensor and connector to the engine control module (ECM) is the same as in the intake air temperature circuit malfunction shown in DTC P0110: INTAKE AIR TEMPERATURE CIRCUIT . If the ECM detects DTC P0115, it operates the fail-safe function in which engine coolant temperature is assumed to be 176°F (80°C). Possible causes are:

• ECT sensor circuit is open and shorted.
• Defective ECT sensor.
• Defective ECM.

After confirming DTC P0115, use the OBD II scan tool or hand-held tester confirm the engine coolant temperature from the CURRENT DATA. See IDENTIFYING ENGINE COOLANT TEMPERATURE CURRENT DATA .