Troubleshooting

DTC P0116 Engine Coolant Temperature Circuit Range/Performance Problem

CIRCUIT DESCRIPTION

DTC Detection Condition:

A thermistor built into the engine coolant temperature sensor changes the resistance value according to the engine coolant temperature.

The structure of the sensor and connection to the ECM is the same as in the intake air temperature circuit malfunction.

MONITOR DESCRIPTION

Monitor Strategy:

Typical Enabling Conditions:

Typical Malfunction Thresholds:

Component Operating Range:

P0116
The engine coolant temperature (ECT) sensor is used to monitor the engine coolant temperature. The ECT sensor has a thermistor that varies its resistance depending on the temperature of the engine coolant. When the coolant temperature is low, the resistance in the thermistor increases. When the temperature is high, the resistance drops. The variations in resistance are reflected in the voltage output from the sensor. The ECM monitors the sensor voltage and uses this value to calculate the engine coolant temperature. When the sensor output voltage deviates from the normal operating range, the ECM interprets this as a fault in the ECT sensor and sets a DTC.

Examples:
1. Upon starting the engine, the ECT is between 35 °C (95 °F) and 60 °C (140 °F). If, after driving for 250 seconds, the ECT still remains within 3 °C (5.4 °F) of the starting temperature, a DTC will be set. (2 trip detection logic)
2. Upon starting the engine, the ECT is over 60 °C (140 °F). If, after driving for 250 seconds, the ECT still remains within 1 °C (1.8 °F) of the starting temperature, a DTC will be set (6 trip detection logic).

Step 1 - 2:

INSPECTION PROCEDURE

HINT:
- If DTCs P0115, P0116 and P0125 are output simultaneously, engine coolant temperature sensor circuit may be open. Perform troubleshooting of DTC P0115 first.
- Read freeze frame data using hand-held tester or OBD II scan tool. Because freeze frame records the engine conditions when the malfunction is detected. When troubleshooting, it is useful for determining whether the vehicle was running or stopped, the engine was warmed up or not, the air-fuel ratio was lean or rich, etc. at the time of the malfunction.