Engine coolant temperature sensor
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Engine coolant temperature sensor
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The temperature sensor is located in the intake manifold between the 3rd and 4th pipe 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 5 V from pin 68 through a 2.74 kohm resistor integrated in the control module. The sensor is grounded via control module pin 67.
In order to obtain a precise temperature reading, the control module takes in a reference ground from the sensor ground lead on pin 66. The voltage across the resistor in the control module is proportional to the coolant temperature.
Engine coolant temperature is used to:
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calculate the injection duration for pre-injection
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calculate the injection duration while the starter motor is cranking
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calculate after-start enrichment.
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determine when closed loop should be engaged
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determine the requested idling speed.
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If the sensor voltage is too low, diagnostic trouble code P0117 will be generated.
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If the sensor voltage is too high, diagnostic trouble code P0118 will be generated.
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If the temperature value is implausible, diagnostic trouble code P0125 will be generated.
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System reaction to a fault
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A substitute value is selected that is equal to the temperature of the intake air on starting and increased with 1 °C (1.8 °F) for each 150th engine revolution. The substitute temperature is limited to 90 °C.
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Fuel adaptation blocked.
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