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Monitoring catalytic converter efficiency, function - GF49.10-P-3033AM

ENGINE 113.990 in MODEL 211, 219 

ENGINE 113.991 in MODEL 215, 220 

ENGINE 113.992 in MODEL 230 up to Model Year 2008 /AEJ 07 

ENGINE 113.993 in MODEL 463 up to 31.5.12 

ENGINE 113.995 in MODEL 230 up to Model Year 2008 /AEJ 07 

Fig 1: Identifying Catalytic Converter Efficiency Monitor Function Diagram
G07873694Courtesy of MERCEDES-BENZ USA

The firewall catalytic converters are assessed concerning their capacity to store oxygen. When the firewall catalytic converters are at operating state temperature and the lambda control has been enabled, the amplitude of O2 sensor signals downstream of the firewall catalytic converters are compared with the O2 sensor signal upstream of the firewall catalytic converters. Changes in the oxygen content downstream of the firewall catalytic converters are almost completely dampened by the high oxygen storage capacity of the firewall catalytic converters. This results in the O2 sensor signal downstream of the firewall catalytic converters being virtually constant (small amplitude).

If the firewall catalytic converter is no longer operational, the O2 sensor signal upstream and downstream of the firewall catalytic converters will be equal.

Several measurements must be performed in the specified engine speed and load range. The results are compared with a performance map from the ME-SFI [ME] control unit and recognized error are stored in the fault memory.

If a fault is detected, the engine diagnosis indicator lamp or USA ONLY the "CHECK ENGINE" indicator lamp is lit on the instrument cluster.

IMPORTANT The stored faults can be read out and deleted with STAR DIAGNOSIS.

  O2 sensors, location/task/design/function   GF07.04-P-4103AM
  ME-SFI control unit, location/task/design/function   GF07.61-P-5000AM
  Exhaust system, location/task/design/function   GF49.00-P-2000AM 
  Three-way catalytic converter, location/task/design/function   GF49.10-P-3002AM 
  "CHECK ENGINE" indicator lamp, location/task/function At USA ONLY GF54.30-P-4101AM
  Engine diagnosis indicator lamp - location/task/function except USA ONLY GF54.30-P-4102AM