P0118

CIRCUIT DESCRIPTION

Schematic:

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
^ No IAT sensor DTCs are 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 (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

NOTE: Refer to Connector Test Adapter Kit J 35616-A Notice in Service Precautions.

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

TEST DESCRIPTION

Steps 1 - 10:

Steps 11 - 15: