P0118

DIAGNOSTIC TROUBLE CODES P0117, P0118
Coolant temperature sensor, control module input, open circuit or shorting to ground/batt+.

Fault Symptom.
CHECK ENGINE lamp (MIL) on, reluctance to start when cold.

Condition
In the case of a short circuit or open circuit a diagnostic trouble code will be generated if the temperature of the intake air is above -10°C (14°F).

Diagnostic Procedure.
1. Check the operation of the temperature sensor using an ISAT scan tool.
Ignition switch in the ON position.
Select "READ FUNCTIONS".
Select "COOLANT TEMP".
The Scan Tool reading is dependent on the current temperature of the engine:
- If there is an open circuit the Scan Tool reading will be about -70°C and,
- If there is a short circuit it will be about +160°C.

If the measured value is correct, continue with step 5.
If the measured value is incorrect, continue with step 2.





2. Check the electrical interface in the temperature sensor connector.
Unplug the 2-pole connector.
Ignition switch in the ON position.
Take a voltage reading in the female connector as follows:
- across pin 1 and Batt - ______ about 5 V.
- across pin 2 and Batt + ______ about 12 V.
Measure the amperage (mA) in the female connector as follows:
- across pins 1 and 2 ______ about 5 mA.
The measurements above are to show whether the ECM and the wiring as far as the temperature sensor are in good condition and functionally OK.

If all the measured values are correct, continue with step 3.
If any measured value is incorrect, continue with step 4.

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3. The temperature sensor may be suspected of being faulty.
Check the temperature sensor's connector for corrosion and possibly remedy it.
Then check the temperature sensor's resistance.
Take resistance readings in the temperature sensor's connector.
Nominal resistances are shown on table:





If the measured value is incorrect, fit a new the temperature sensor.
If the measured value is correct, continue with step 5.

4. Check The Wiring between the temperature sensor's 2-pin connector and the control module for continuity.
Check the leads for open circuit, shorting and possible stray currents.

If the measured values are correct, continue with step 5.

5. Clear the diagnostic trouble code and drive the car to see whether the DTC is generated again.

If the diagnostic trouble code is generated again, continue at "Procedure Before ECM Replacement". Component Tests
If the trouble code is not generated again the remedial measure taken was correct, otherwise the fault is of intermittent type.