P0118

Diagnostic Chart:

Schematic:

Temperature Vs Resistance:

The engine coolant temperature sensor 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. This sensor is used for fuel/ignition control, hot/low coolant light, coolant gage and fan. TCC, and EVAP canister purge valve.

DTC PARAMETERS
DTC P0118 will set if the ECT reads less than -40°C (-40°F) for 6.25 seconds when the engine has been running over 60 seconds.

IMPORTANT: The ECT signal is continuously checked when ignition is On.

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.

The PCM will turn the cooling fans On if an ECT diagnostic trouble code is set.

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