P0421

P0421

Diagnostic information - DME V6 DFI

Primary catalytic converter, bank 1, inadequate effect

NOTE: Do not use contact spray on the oxygen sensor's plug connections as this will result in irreparable damage to the lines (blockage of reference air duct).

NOTE: Do not interchange the oxygen sensor ahead of catalytic converter with the sensor behind the catalytic converter as this will result in implausible fault entries.

Diagnostic conditions
- Perform following short tests in sequence:
1. All models: Oxygen-sensor short tests
2. Short test Basic mixture adaptations
3. Short test Catalytic-converter conversion

or

- Battery voltage between 10 V and 16 V
- Temperature when engine started higher than -15 °C (5 °F)
- Time after engine starts > 10 seconds
- Catalytic converter temperature between 500 °C (932 °F) and 900 °C (1,652 °F)
- 50 seconds of driving with a load range between 18% and 56%
- Loading of activated carbon filter less than 8
- Engine speed between 1,000 rpm and 3,000 rpm
- Lambda control ahead of catalytic converter active
- Lambda control behind catalytic converter ready for operation
- No other mixture faults stored

Possible fault causes
- If an oxygen sensor fault is entered::
- corresponding fault cause
- Remedy oxygen-sensor fault according to instructions
then
- then perform short test as described above

- Leak in exhaust system between engine and oxygen sensor behind catalytic converter
- Oxygen sensors in front of and behind catalytic converter are interchanged
- Catalytic converter faulty