P1115

PREHEATING OF FRONT HEATED OXYGEN SENSOR





Fault Symptom.
CHECK ENGINE lamp (MIL) on.

Conditions.
P1102
Preheating current >2600 mA after 150 seconds.

P1115
Preheating current <600 mA after 150 seconds.

Diagnostic Help.
If the ISAT scan tool shows diagnostic trouble codes P1115 and P1117, the fault is probably due to:
- Preheating not working and fuse 38 having blown.
- The lead between pin 8 of H33-4 and pin 87 of the pump relay.

The preheating current can be ascertained with the ISAT scan tool.

Check The Wiring.
Intermittent faults may occur as a result of temporary short circuits and breaks in the wiring. Jiggle the wiring at several points and in different directions to ascertain whether the wiring harness, including any connectors, is causing the trouble. Observe the multimeter, ISAT scan tool or test lamp while doing this.





Diagnostic Procedure.

1 Check the fuses

Is fuse 38 intact?

YES:
^ Continue with point 3.
NO:
^ Install a new fuse. Continue with point 2.

2 Check the resistance of the oxygen sensor preheating elements

The engine should have been switched off for at least 5 minutes.
- Unplug the 4-pin connectors of both oxygen sensors.
- Take readings of the resistance of both sensors.
^ pins 1 and 2: 1.8 - 4.0 ohms.

Are the resistance readings OK?

YES:
^ Check and if necessary repair or replace the leads between pin 1 of both oxygen sensor connectors and fuse 38. Continue with point 5.
NO:
^ Change the relevant oxygen sensor. Continue with point 5.





3 Check the preheating element power supply

- Unplug the oxygen sensor's 4-pin connector.
- Start the engine and run it at idling speed.
- Connect the test lamp to: pin 1 and battery negative (B-).
The test lamp should light up.

Did the test lamp light up?

YES:
^ Continue with point 4.
NO:
^ Repair or replace the wiring. Continue with point 5.

4 Check the preheating circuit ground connection

- Connect the test lamp to:
^ Battery positive (B+) and pin 2
The test lamp should light up or start flashing.

Did the test lamp light up or start flashing?

YES:
^ Change the sensor. Continue with point 5.
NO:
^ Check the lead in question and repair or replace it it necessary. Continue with point 5.





5 Final check

- Clear the diagnostic trouble code.
- Implementation of driving cycle:
^ Drive the car at varying engine loads and rpm for 5 minutes.
- Evaluation of driving cycle:
^ Check whether the diagnostic trouble code has recurred.

Has the diagnostic trouble code recurred?

YES:
^ Continue at "Before Replacing a Control Module". Component Tests and General Diagnostics
NO:
^ The steps taken to rectify the fault were correct.