The engine coolant temperature (ECT) sensor is a thermistor that is located in the lower coolant passage of the engine cylinder head. The ECM monitors the voltage drop across the resistor as it varies with the resistance of the sensor. This sensor is used for fuel/ignition control, hot/low coolant light, coolant gage, and fan. A low voltage indicates a high temperature and vice-versa. The ECM sets this DTC if the engine temperature does not reach a calibrated value within a specified time (varies with engine starting temperature).

DTC P0115 will set if the ECT temperature has not reached 37°C (99°F) within 2 and 5 minutes, based on start up ECT temperature.

P0115 is a (type B) DTC.

Caution: To avoid the danger of being burned, do not remove the cap while the engine, radiator, and surge tank are still hot. Scalding fluid and steam can be blown out under pressure.

Important: The ECT signal is continuously checked when ignition is On.

DTC P0115 indicates a lower than normal engine coolant temperature and probably does not indicate a faulty ECT subsystem.

Possible causes:

Start engine and observe ECT reading on scan tool. Under normal conditions, it should rise smoothly to 88°C (190°F).

ECT may be compared to IAT with scan tool if engine has cooled overnight. They should be within 6°C or 10°F of each other with the ignition On and engine Off.