DTC P0116 Engine Coolant Temperature Circuit Range / Performance Problem

DESCRIPTION

A thermistor is built into the Engine Coolant Temperature (ECT) sensor and it changes its resistance value according to the engine coolant temperature.

The structure of the sensor and connection to the ECM is the same as the intake air temperature sensor.

DTC No.	DTC Detection Condition	Trouble Area
P0116	If the engine coolant temperature was between -40°C (-40°F) and 60°C (140°F) at engine start, and condition (a) and (b) are met: (2 trip detection logic) (a) Vehicle is driven at varying speeds (accelerating and decelerating) (b) Engine coolant temperature remains within 3°C (5.4°F) of the engine starting temperature	Engine coolant temperature sensor
P0116	If the engine coolant temperature was more than 60°C (140°F) at engine start, and conditions (a) and (b) are met: (6 trip detection logic) (a) Vehicle is driven at varying speeds (accelerating and decelerating) (b) Engine coolant temperature remains within 1°C (1.8°F) of the engine starting temperature, and this is successively recorded 6 times	Engine coolant temperature sensor

MONITOR DESCRIPTION

The engine coolant temperature sensor is used to monitor the engine coolant temperature. The engine coolant temperature sensor has a thermistor that varies its resistance depending on the temperature of the engine coolant. When the coolant temperature is low, the resistance of 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's voltage output varies slightly, the ECM interprets this as a fault in the engine coolant temperature sensor and sets a DTC.

Examples:

Upon starting the engine, the engine coolant temperature was between -40°C (-40°F) and 60°C (140°F). If after driving for a few minutes, the engine coolant temperature still remains within 3°C (5.4°F) of the staring temperature, a DTC will be set. (2 trip detection logic)

Upon starting the engine, the engine coolant temperature was over 90°C (194°F). If after driving for a few minutes, the engine coolant temperature still remains within 1°C (1.8°F) of the starting temperature, a DTC will be set. (6 trip detection logic)

INSPECTION PROCEDURE

HINT:

If DTCs P0115, P0116, P0117, and P0118 are output simultaneously, the engine coolant temperature sensor circuit may have an open or short. Perform troubleshooting for those DTCs first.

1.REPLACE ENGINE COOLANT TEMPERATURE SENSOR

LEXUS IS250, IS220d / GSE20 ALE20

2AD-FHV ENGINE CONTROL SYSTEM

Lexus IS250 IS220d GSE20 ALE20

ECD SYSTEM