P0117

Diagnostic Chart:

Schematic:

Temperature Vs Resistance:

The Engine Coolant Temperature Sensor (ECT) is a thermistor type sensor. When coolant temperature is cold the sensor has a high resistance, as temperature increases the resistance of the sensor decreases. The PCM provides a 5 volt signal to the coolant sensor, which is also connected to PCM ground. The PCM reads the voltage drop on the signal line to determine coolant temperature.

DTC PARAMETERS
DTC P0117 will set if the ECT reads above 138°C (280°F) for 6.25 seconds when the engine has been running longer than 128 seconds.

IMPORTANT: The ECT signal is continuously checked when the engine is running.

DIAGNOSTIC AIDS
Start engine and observe ECT reading on Scan tool. Normal operation is for the ECT to rise smoothly to approximately 83°C (180°F), as thermostat opens then stabilizes.

Visually inspect ECT wires for damage. Wiggle wires while observing Scan tool ECT reading and watch for a sudden shift in temperature. The PCM will turn the cooling fans On if an ECT diagnostic trouble code is set.

ECT may be compared to IAT temperature, with a Scan tool if engine has cooled overnight at ambient temperature. They should be relatively close to each other with ignition On - engine Off.