DTC P0116-Engine Coolant Temperature Sensor Circuit Performance: Notes

Fig 1: Engine Coolant Temperature Sensor Circuit - Circuit Diagram

Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.

For a complete wiring diagram, refer to appropriate SYSTEM WIRING DIAGRAMS article.

Theory of Operation 

Engine Coolant Temperature Sensor performance looks at the outputs of three temperature sensors and compares them under cold start conditions. Following a start to run delay time, the outputs of the ambient, engine coolant, and intake air temperature sensors will be compared. If the intake air and ambient air temperature sensors agree and the engine coolant temperature does not agree, the engine coolant temperature sensor is declared as irrational. 

• When Monitored: 

  Engine off time is greater than 480 minutes. Ambient temperature is greater than 4 deg C (38 deg F). 

• Set Condition: 

  After a calibrated amount of cool down time the PCM compares the ECT Sensor, IAT Sensor, and the Ambient Air Temp Sensor values. If the ECT Sensor value is not within 10 deg C of the other two temperature sensors. Two Trip Fault. Three good trips to turn off the MIL. 

Always perform the PRE-DIAGNOSTIC TROUBLESHOOTING PROCEDURE before proceeding.