P0118

Diagnostic Chart:

Wiring Diagram:

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

CONDITIONS FOR SETTING THE DTC
- Engine running for at least 8 minutes.
- ECT less than -40°C (-40°F).
- Conditions met for 2 seconds.

ACTION TAKEN WHEN THE DTC SETS
Idle increase.

CONDITIONS FOR CLEARING THE MIL/DTC
- The PCM will turn the MIL off after three consecutive trips without a fault condition.
- A History DTC will clear when forty consecutive warm-up cycles that the diagnostic does not fail (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.

DIAGNOSTIC AIDS
Check harness routing for a potential short to ground. After 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
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 faulty PCM.