| CAUTION | If ECM replacement is instructed in following testing, always ensure ECM connectors and ground circuits are okay. If either are suspect, repair and repeat testing to confirm ECM malfunction. |
Note. If DTCs P0110, P0115, P0120, P0440, P0441, P0446, P0450 and P0451 are output together, inspect ECM E2 circuit (sensor ground) between ECM and splice I8. Repair as necessary. See WIRING DIAGRAMS article.
Note. For component location, see appropriate illustration in THEORY & OPERATION article.
Circuit Description
Engine Coolant Temperature (ECT) sensor is a thermistor sensor which monitors engine coolant temperature. DTC is set when ECM detects an open or short in ECT sensor circuit. ECM will operate in fail-safe mode if DTC P0115 is set. Possible causes are
- ECT sensor circuit is open or shorted.
- Defective ECT sensor.
- Defective ECM.
Diagnostic Aids
After confirming DTC P0115, use scan tool to access CURRENT DATA to confirm engine coolant temperature. If ECT sensor value displayed on scan tool is always -40°F (-40°C), ECT sensor circuit may be open. If ECT sensor value displayed on scan tool is always 284°F (140°C) or more, ECT sensor circuit may be shorted. Using scan tool, read FREEZE FRAME data. Freeze frame data records engine conditions when malfunction is detected.