Note. If DTCs P0115 and P0116 are output together, an open may exist in Engine Coolant Temperature (ECT) sensor circuit. Perform DTC P0115: ENGINE COOLANT TEMPERATURE 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.
- Cooling system malfunction.
Diagnostic Aids
Using Toyota hand-held tester or scan tool, read FREEZE FRAME data. Freeze frame data records engine conditions when malfunction is detected.