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• P0303

  P0303

  
  

  Diagnosis information - DME V6 DFI Misfire detection Cylinder X

  NOTE:

• The fault P0300 >>Misfire totals fault<< indicates that an exhaust-related misfire has been detected for at least 1 cylinder.
• An initial indication appears because the relevant cylinder(s) is/are stored.
  
  

  NOTE:

• Diagnosis detects uneven running for the specified cylinder.
• Uneven running is calculated from the expected and actual crankshaft acceleration due to combustion.
• Uneven running is interpreted as a misfire or valve lift fault, depending on type.
  
  

  NOTE:

• A cycle of 1,000 crankshaft revolutions is evaluated for exhaust-relevant misfires.
• The cycle is 200 revolutions for misfiring rates that will damage the catalytic converter.
• The misfiring rates are compared with a threshold value.
• If the misfiring rate is greater than the threshold value, the fault is set.
• The >>Check Engine<< warning light flashes if the misfiring rate has the potential to cause permanent catalytic converter damage.
  
  

  NOTE:

• It is possible that only one cylinder (or the cylinders of one bank) has/have exceeded the uneven running threshold for a fault entry.
• However, other cylinders may also be just below the level which would result in a fault entry.
• A comparison of the actual values for >>Uneven running<< of the individual cylinders can provide further information here.
  
  

  NOTE:

• If the battery or the DME (DFI) control unit was disconnected during troubleshooting, sensor wheel adaptation (range 1) must be carried out.
• It is only when this is done that misfires can be reliably detected by the DFI.
• For this purpose, it is necessary to accelerate three times in second gear and then to allow the vehicle to coast to a stop without changing gear, braking or accelerating (overrun fuel cut-off phase).
• It is possible to establish whether adaptation has been performed by reading out [[Adaptation status]] under [[Actual values]] in the PIWIS Tester.
  
  

  Diagnostic conditions

• Engine temperature > -20 °C (-4 °F)
• Engine speed 400 rpm ... 6700 rpm
• Engine load between 10 % and 38 %
• No crankshaft sensor fault P0335, P0336, P0371 or P0373 detected
  
  

  Possible fault causes

• Use of an engine-block heater
  
  
• Lines, power or ground supply faulty for electrical components listed below (loose contact, oxidation, etc.)
• Lines, power or ground supply faulty for DME control unit (DFI) (loose contact, oxidation, etc.)
  
  
• Wrong spark plug installed
• Mechanical or electrical fault in spark plug
• Ignition rod module faulty
  
  
• Tank filled with incorrect fuel quality
• Tank driven empty
• Water in tank
• Fuel filter soiled / blocked
• Mechanical fault in fuel pump
  
  
• Mechanical or electrical fault in fuel injector(s)
• Oxygen sensor faulty
  
  
• Exhaust system faulty - flow severely restricted
• Muffler blocked / faulty
• Kink in exhaust pipe
• Catalytic converter damage
  
  
• Leak in intake-air distributor
• Fault in adjustment of intake camshaft timing (VarioCam)
• Fault in adjustment of exhaust camshaft timing (VarioCam)
• Timing not correct
• Hydraulic tappet faulty
• Valve seat or valve faulty
• Mechanical engine fault