Note. If DTCs P0115 and P0116 are output together, an open may exist in ECT sensor circuit. Perform DTC P0115: ENGINE COOLANT TEMPERATURE (ECT) SENSOR CIRCUIT test before performing DTC P0116 test.
Note. For component location, see appropriate illustration in THEORY & OPERATION article.
Circuit Description
ECT sensor is a thermistor sensor which monitors engine coolant temperature. DTC is set when ECT sensor signal value is out of range during engine operation. Possible causes are
- Defective ECT sensor.
- Defective cooling system.
Diagnostic Aids
After confirming DTC P0116, 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), ECT sensor circuit may be shorted. Using scan tool, read freeze frame data. Freeze frame records engine conditions when malfunction is detected.