P0118

Diagnostic Chart (Part 1 Of 2):

Diagnostic Chart (Part 2 Of 2):

Schematic:

CIRCUIT DESCRIPTION
The Engine Coolant Temperature (ECT) sensor is a thermistor, or variable resistor, that measures the temperature of the engine coolant. The PCM supplies 5 volts to the ECT signal circuit through a pull-up resistor. When the engine coolant temperature is cold, the sensor resistance is high. When the engine coolant temperature increases, the sensor resistance lowers. With high sensor resistance, the PCM detects a high voltage on the ECT signal circuit. With lower sensor resistance, the PCM detects a lower voltage on the ECT signal circuit. If the PCM detects an excessively high ECT signal voltage (a low temperature indication), DTC P0118 will set.

CONDITIONS FOR RUNNING THE DTC
^ IAT sensor DTCs are not set.
^ The engine has been running for 60 seconds.
^ Intake air temperature is more than 7°C (19°F).

CONDITIONS FOR SETTING THE DTC
^ The ECT sensor signal voltage is more than 4.9 volts. The temperature would be approximately -37°C (-35°F).
^ The conditions exists for less than 1 second.

ACTION TAKEN WHEN THE DTC SETS
^ The PCM illuminates the Malfunction Indicator Lamp (MIL) during the second consecutive trip in which the diagnostic test runs and fails.
^ The PCM stores the conditions present when the DTC set as Freeze Frame and Fail Records data.

CONDITIONS FOR CLEARING THE MIL/DTC
^ The PCM will turn the MIL OFF after the third consecutive trip in which the diagnostic runs and passes.
^ The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
^ The DTC can be cleared by using the scan tool Clear DTC Information function.

DIAGNOSTIC AIDS
For intermittent conditions, refer to DTC P1115 Engine Coolant Temperature (ECT) Sensor Circuit Intermittent High Voltage and/or Symptoms. P1115 Symptom Related Diagnostic Procedures