P0117

Wiring Diagram:

ECT Sensor Circuit Low Voltage/High Temp:

P0117 - ECT SENSOR CIRCUIT LOW VOLTAGE/HIGH TEMP
The engine coolant temperature (ECT) sensor is a thermistor that varies resistance according to changes in engine coolant temperature. The ECM supplies a five-volt reference through a pull-up resistor to the sensor. which is connected to ground. When the sensor is cold it has high resistance (high signal voltage at ECM). As the sensor temperature increases, its resistance decreases (lower signal voltage at ECM). The ECM uses the signal voltage to determine engine coolant temperature. DTC P0117 sets when the ECT sensor signal voltage at the ECM is below the calibrated voltage value (over the calibrated temperature value).

DTC PARAMETERS

DTC P0117 will set if ECT sensor temperature is over 140°C (284°F)when
^ Condition exists for longer than 0.5 seconds
^ Engine speed is greater than 20 rpm

DTC P0117 diagnostic runs continuously with engine cranking/running.

P0117 is a type B DTC

DIAGNOSTIC AIDS
To locate an intermittent problem, use Scan tool to monitor ECT sensor temperature with ignition On, engine Off.

Wiggling wires while watching for a change in ECT sensor temperature may locate the area where a short to ground may exist.

Engine coolant leaking from the sensor into the sensor connector will cause a shorted condition across the sensor terminals resulting in an elevated temperature.

The Coolant Temperature gauge will display COLD if DTC P0117 is active.

The ECM will command the cooling fans On if DTC P0117 is active.

Refer to ECT General Description for a Temperature vs. Resistance chart.