Note. If DTCs P0115, P0116, P0117, P0118 and P0125 are output simultaneously, an open may exist in wiring between Engine Coolant Temperature (ECT) sensor and Engine Control Module (ECM). Perform DTC P0115, DTC P0117 &/OR DTC P0118 test before performing DTC P0116 test.
Circuit Description
Engine Coolant Temperature (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 thermostat.
Diagnostic Aids
Using Toyota hand-held tester or scan tool, read FREEZE FRAME data. Freeze frame data records engine conditions when malfunction is detected.