P0118

Diagnostic Chart:

Wiring Diagram:

CIRCUIT DESCRIPTION
The Engine Coolant Temperature (ECT) sensor is a thermistor that controls the signal voltage to the PCM. When the engine is cold, the sensor resistance is high, therefore the PCM will see a high signal voltage. As the engine warms, the sensor resistance becomes less and the voltage drops. The voltage measured across the thermister is interpreted as a temperature. This is a type B DTC.

CONDITIONS FOR SETTING THE DTC
^ The engine has been running for at least 8 minutes.
^ The ECT is less than -30°C (-22°F).
^ The conditions were met for 2 seconds.

ACTION TAKEN WHEN THE DTC SETS
Idle increase.

CONDITIONS FOR CLEARING THE MIL/DTC
^ The PCM will turn the Malfunction Indicator Lamp (MIL) off after three consecutive trips without a fault condition.
^ A History DTC will clear after forty consecutive warm-up cycles during which the diagnostic does not fail (the coolant temperature has risen 5°C (40°F) from start up coolant temperature and engine coolant temperature exceeds 71°C (160°F) that same ignition cycle).
^ Use of a Scan Tool will clear the DTC codes.

DIAGNOSTIC AIDS
Check the harness routing for a potential short to voltage. After the engine is started, the ECT temperature should rise steady to about 85°C (185°F). A mis-scaled sensor could result in poor driveability complaints.

TEST DESCRIPTION
The number(s) below refer to step number(s) on the Diagnostic Table.
2. This test determines if P0118 is an intermittent condition.
3. This test will determine if signal circuit is open, or a malfunctioning PCM.