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• 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