Toyota Corolla (E120) 2002–2008 Repair Manual / Diagnostics / Sfi system / Engine coolant temp. Circuit range/performance problem / Circuit description

Toyota Corolla (E120): Circuit description

Refer to dtc p0115

Dtc no.	Dtc detection condition	Trouble area
P0116	If engine coolant temperature (ect) was between 35 c (95 °F) and 60 c (140 °F) when starting the engine, and also conditions (a) and (b) are met:  vehicle has run with acceleration and deceleration  etc still remains within 3 c (5.4 °F) of the starting temperature (2 trip detection logic)	Engine coolant temperature sensor
	If engine coolant temperature (ect) was more than 60 c when starting the engine, and also conditions (a) and (b) are met:  vehicle has run with acceleration and deceleration  ect still remains within 1 c (1.8 °F) of the starting temperature (6 trip detection logic)

Monitor description

The engine coolant temperature (ect) sensor is used to monitor the engine coolant temperature. The ect sensor has a thermistor that varies its resistance depending on the temperature of the engine coolant. When the coolant temperature is low, the resistance in the thermistor increases. When the temperature is high, the resistance drops. The variations in resistance are reflected in the voltage output from the sensor. The ecm monitors the sensor voltage and uses this value to calculate the engine coolant temperature. When the sensor output voltage deviates from the normal operating range, the ecm interprets this as a fault in the ect sensor and sets a dtc.

Examples:

1.  upon starting the engine, the coolant temperature (ect) was between 35 c (95 °F) and 60 c (140 °F).

   If after driving for 250 seconds, the ect still remains within 3 c (5.4 °F) of the staring temperature, a dtc will be set. (2 Trip detection logic)

2.  upon starting the engine, the coolant temperature (ect) was over 60 c (140 °F). If after driving for 250 seconds, the ect still remains within 1 c (1.8 °F) of the starting temperature, a dtc will be set. (6 Trip detection logic)

Monitor strategy

Typical enabling conditions

Typical malfunction thresholds

Component operating range

Wiring diagram

Refer to dtc p0115