P0422

THREE WAY CATALYTIC CONVERTER, CYL BANK 1 (REAR)





Fault Symptom.
CHECK ENGINE lamp (MIL) on.

Conditions.
Voltage signal changes from the rear heated oxygen sensor are compared with the voltage signal changes from the front heated oxygen sensor and corrected in respect of engine load and rpm.

Three Way Catalytic Converter Heating
Vehicle speed ~70 km/h for three minutes and 20 seconds.

Evaluation Of The Three Way Catalytic Converter
Gentle acceleration from idling speed up to 2000-2500 rpm and then constant engine load and speed between 2000 and 2500 rpm for a total of three minutes and 20 seconds.

Diagnostic Help.
A temporary or permanent decrease in the capacity of the three way catalytic converter may be caused by:
^ leaded fuel or fuel with a sulphur content.
^ fuel additives.
^ additives in the engine oil if oil consumption is abnormal.

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 exhaust system

- Start the engine and run it at idling speed.
- Check the exhaust system for leakage between the engine and the rear heated oxygen sensor.

Any leakage?
YES: Rectify the fault and continue with point 3
NO: Change the three way catalytic converter. Then continue with point 2.





2. Check the fuel system

- Check the fuel pressure and fuel pump flow capacity.

Are the readings OK?
YES: Continue with point 3
NO: Rectify the fault and then continue with point 3.





3. Final check

- Clear diagnostic trouble codes.