Note. If DTCs P0115 and P0116 are output simultaneously, an open may exist in wiring between Engine Coolant Temperature (ECT) sensor and Engine Control Module (ECM). Perform DTC P0115: ENGINE COOLANT TEMPERATURE SENSOR CIRCUIT 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
This DTC uses two-trip detection logic. Using Toyota hand-held tester or scan tool, read FREEZE FRAME data. Freeze frame data records engine conditions when malfunction is detected.