Possible causes

– Low engine coolant level
– Faulty Engine Coolant Temperature (ECT) sensor
– Faulty engine coolant thermostat
– Engine Coolant Temperature (ECT) sensor harness is open or shorted
– Engine Coolant Temperature (ECT) sensor circuit poor electrical connection

When is the code detected?

Coolant temperature signal sent to the ngine Control Module (ECM) is not within specified range.

Symptoms

– Engine Light ON (or Service Engine Soon Warning Light)

P0116 TOYOTA Description

The Engine Coolant Temperature (ECT) sensor is used to detect the engine coolant temperature. The sensor modifies a voltage signal from the Engine Control Module (ECM). The modified signal returns to the ECM as the engine coolant temperature input. The sensor uses a thermistor which is sensitive to the change in temperature. The electrical resistance of the thermistor decreases as temperature increases.

TOYOTA Technical Service Bulletins for P0116 code