P0117

DESCRIPTION
The Engine Coolant Temperature (ECT) sensor is located in the coolant passage of the cylinder head. The ECT sensor is a variable resistor whose resistance changes as the temperature of the engine coolant flowing past the sensor changes. When coolant temperature is low, sensor resistance is high; when coolant temperature is high, sensor resistance is low.
The Engine Control Module (ECM) checks ECT sensor voltage and uses the information to adjust fuel injector pulse width and ignition timing. When the temperature sensed is very cold, the ECM enriches the fuel mixture and advances ignition timing. As coolant temperature rises, the ECM reduces the amount of enrichment and timing advance.




FAILURE CONDITION
The ECM will set P0116 and the Malfunction Indicator Lamp (MIL) will turn on if either of the two following problems is detected during two driving cycles:
- The ECT sensor reports an out of range temperature (below -49 °F or above 284 °F (-45 °C or 140 °C) for more than 0.2 seconds.
- The ECT sensor's actual performance curve falls more than 68 °F (20 °C) below the ECM's model curve (based on ambient air temperature and elapsed time after a cold start) for more than 0.2 seconds.
This code indicates an extremely high or low temperature, or uncharacteristic engine temperature performance being read by the ECT sensor or ECM.

The ECM will set P0117 and the Malfunction Indicator Lamp (MIL) will turn on if the ECT sensor reports a temperature below -49 °F (-45 °C) for 0.2 seconds during two driving cycles.

The ECM will set P0118 and the Malfunction Indicator Lamp (MIL) will turn on if the ECT sensor reports a temperature above 284 °F (140 °C) for 0.2 seconds during two driving cycles.

NOTE: The ECT sensor resistance varies with temperature as follows:
- 5900 ohms @ 32°F (0°C).
- 2500 ohms @ 68°F (20°C).
- 300 ohms @ 176°F (80°C).

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TEST PROCEDURE