| CAUTION | If ECM replacement is instructed in following testing, always ensure ECM harness connector and ground circuit are okay. If either are suspect, repair and repeat testing to confirm ECM malfunction. If ECM is replaced, ECM must be programmed with proper ignition key code for engine immobilizer system. For programming procedures, see COMPUTER RELEARN PROCEDURES article in GENERAL INFORMATION. |
Circuit Description
The ECT sensor is a thermistor that monitors coolant temperature. DTC P0116 is set when after engine has been running for predetermined amount of time, sensor value is out of specified range. Possible causes are
- Faulty ECT sensor.
- Engine cooling system fault.
Note. If DTCs P0115 and P0116 are output together, inspect ECT circuits for an open. Repair as necessary. See WIRING DIAGRAMS article. Repair DTC P0115 first.
Diagnostic Aids
After confirming DTC P0116, use scan tool to access CURRENT DATA to confirm engine coolant temperature. If temperature displayed on scan tool is -40°F (-40°C), ECT sensor circuit may be open. If temperature displayed on scan tool is 284°F (140°C) or more, ECT sensor circuit may be shorted. Using scan tool, read freeze frame data. Freeze frame records engine conditions when malfunction is detected.