P0115

Schematic:

The Engine Coolant Temperature (ECT) sensor is a thermistor that varies resistance according to changes in engine coolant temperature. The ECM supplies a five volt reference through a pull up resistor(s) to the sensor, which is connected to ground. When the sensor is cold it has a high resistance (high signal voltage at ECM). As the sensor temperature increases, its resistance decreases (low signal voltage at ECM). The ECM uses the signal voltage to determine engine coolant temperature. DTC P0115 sets when the calculated accumulated airflow exceeds the predicted accumulated airflow when the engine coolant temperature has reached a calibrated temperature (more air will flow through a cold engine then when the engine is warm).

DTC PARAMETERS
DTC P0115 will set if the calculated accumulated airflow has been exceeded (based on predicted airflow) when ECT temperature has reached 37°C (99°F) when engine has been running between 2 and 5 minutes.

DTC P0115 runs once per ignition cycle once the above conditions have been met.

P0115 is a (type B) DTC

DIAGNOSTIC AIDS
DTC P0115 indicates lower than normal engine coolant temperature, which most likely was NOT caused by a short/open or intermittent short/open in the ECT wiring.

Possible causes of low engine coolant temperature:
^ Thermostat stuck open
^ Cooling fan(s) always On
^ Very low ambient temperatures
^ Corrosion in connector or resistance in wiring
^ Skewed sensor

ECT sensor reading may be compared to IAT sensor reading on Scan tool after the vehicle has been sitting longer than 6 hours with the ignition Off. Both readings should be within 6°C or 10°F of each other.

Refer to ECT General Description for a Temperature vs. Resistance chart.