P0161

PREHEATING, REAR HEATED OXYGEN SENSOR, CYLINDER BANK 2 (FRONT)





Fault Symptom.
CHECK ENGINE lamp (MIL) on.

Conditions.
^ Preheating circuit resistance greater than 10 ohm after 3 minutes.
If an oxygen sensor attains operative status 4 times faster than another one, the other one is identified as defective.

^ Preheating circuit resistance less than 2.5 ohm after 3 minutes.

Diagnostic Help.
If the ISAT scan tool shows diagnostic trouble codes P1115, P1117, P0155 and P0161, the cause of the trouble is:

^ because fuse 28 has blown
^ due to the lead from crimped connection J37 via fuse 28 and connector H70-1 to crimped connection J29.

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.





1. Inspection of fuses

Is fuse 38 intact?

YES: Continue with point 3.

NO: Change the fuse and 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 four 4-pin oxygen sensor connectors.
- Check the resistance of the four sensors
^ pins 3-4: 1.8-4.0 ohm.

Are the resistance readings OK?

YES: Check and if necessary repair or replace the lead between pin 1 in each of the four oxygen sensor connectors and fuse 28. Then continue with point 5.

NO Change the relevant oxygen sensor and proceed to 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 a 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 lead in question and proceed to point 5.

4. Check the preheating circuit ground connection

- With the engine running at idling speed, connect a test lamp to battery positive (B+) and pin 2.

The test lamp should light up or start flashing.

Test lamp on or flashing?
YES: Change the sensor and continue with point 5.
NO: Check the lead in question and repair or replace it if necessary. Then 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 as described at "Before Replacing a Control Module". Component Tests and General Diagnostics
NO: The steps taken to rectify the fault were correct.