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 CONDITIONS
The ECM will set P0116 and the Malfunction Indicator Lamp (MIL) will turn on if the ECT sensor's actual performance curve falls more than 68 °F (20 °C) below the ECM's model curve (based on fuel delivery, ambient air temperature and engine running time) for 0.2 seconds during two driving cycles. This code indicates 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).

Circuit Diagram:

Test Procedure:

Test Procedure Part 1:

Test Procedure Part 2:

Test Procedure: