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Coolant temperature sensor

Coolant temperature sensor





The temperature sensor is located on the left-hand end of the cylinder head and is in contact with the engine coolant. The sensor is NTC type.

The control module measures the coolant temperature by supplying the sensor with 5V through an integrated 1.0 kohm resistor from pin 39. The sensor is grounded via pin 22. The voltage across the resistor in the control module is proportional to the temperature of the coolant.

Engine coolant temperature is used to:


calculate the injection duration for pre-injection.

calculate the injection duration while the starter motor is cranking.

calculate after-start enrichment.

determine when closed loop should be engaged.

correct idling speed.




Diagnostics


If the sensor voltage is too low, diagnostic trouble code P0117 will be generated.

If the sensor voltage is too high, diagnostic trouble code P0118 will be generated.


System reaction to a fault


A substitute value that equals the intake air temperature at start is selected and then increased with 1°C (1.8°F) for every 150 engine revolutions.

Purging blocked.