P0115

DTC's P0115, P0117, P0118:

DIAGNOSTIC TROUBLE CODES PO115, P0117, PO118
ENGINE COOLANT TEMPERATURE SENSOR, MALFUNCTIONING OR NOT WORKING AT ALL

Symptoms of fault
The malfunction indicator lamp is on.
Deterioration in driveablity.
Difficult to start engine from cold.

Conditions.
If there is a short circuit/open circuit, a DTC will be generated after 5 seconds.

Diagnostic procedure
1. Check the operation of the temperature sensor using an ISAT scan tool.

- Ignition switched ON.
- Connect the ISAT scan tool and select the "COOLANT TEMP" command on the "READ FUNCTIONS" menu.

The ISAT display depends on the prevailing engine temperature.

Note that the ECM adopts the substitute value of 26°C if there is an internal temperature sensor fault. This value is shown on the ISAT where appropriate.

"ICE" can be selected on the ISAT and the "COOLANT TEMP" command on the "READ VALUES" menu for reference. Because of tolerances in the two temperature sensors, the ISAT scan tool readings may differ by ± 5°C.

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

DTC's P0115, P0117, P0118:

2. Check the electrical interface in the temperature sensor connector.

- Unplug the 2-pole connector.
- Measure the voltage in the female connector.
^ Pin 2 to Batt - _______ approx. 5 V.
^ Batt + to pin 1 _______ approx. 12 V.
- Measure the current (mA) in the female connector.
^ Pin 2 to pin 1 ______ approx. 1.8 mA.

The measurements above are to show whether ECM including wiring as far as the temperature sensor are operating correctly.

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

3. Check the resistance of the temperature sensor.

- Carry out resistance measurement in the temperature sensor's connector.

The nominal resistance values are:

°C °F Resistance (kOhms)

-30 -22 20 - 30
-10 14 7.0 - 11.4
20 68 2.1 - 2.9
40 104 1.0 - 1.3
60 140 0.565 - 0.670
80 176 0.295 - 0.365
90 194 0.24 - 0.26
110 230 0.14 - 0.16

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

DTC's P0115, P0117, P0118:

4. Check the continuity of the wiring between the ECM and the 2-pole connector of the temperature sensor.

- Check the leads for open circuits, short circuits and any stray current.
- If the measured values are correct, continue with step 5.

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

- If the diagnostic trouble code is registered, continue at "Procedure before replacing ECM".
- If the diagnostic trouble code is not registered, the action taken is correct. Otherwise the fault is intermittent in nature.