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ME-SFI two-sensor control, function - GF07.61-P-3020BK

ENGINES 113.967 in MODEL 219 

ENGINES 113.964 in MODEL 164.1 up to Model Year 08/Modification Year 07 

ENGINES 113.971 in MODEL 251 up to Model Year 08/Modification Year 07 

Shown on model 219 

Fig 1: ME-SFI Two-Sensor Control Function Diagram
G07302063Courtesy of MERCEDES-BENZ USA

The ME engine control unit determines the lambda mean value from signals from the O 2 sensors downstream of TWC. This value is compared with a stored value for optimum exhaust emissions.

If the deviation is too large after a number of measurements, a correction variable (delay time) is determined for the lambda control.

The correction variable (value for new O 2 sensor upstream TWC approx. 0) makes it possible to compensate for aging of the O 2 sensor upstream of TWC within certain limits. If the correction variable exceeds the limit value, the O 2 sensor upstream of TWC must be replaced.

The correction values are map-controlled and are implemented by the ME control unit by adapting the fuel injection.

Two sensor control is only enabled when the catalytic convertors have reached their operating temperature and the O 2 sensors downstream of TWC are correct.

If the limit values are exceeded or the plausibility check of the O 2 sensor signals is negative, a fault is stored in the fault memory. The stored faults can be read out and erased with the STAR DIAGNOSIS.

IMPORTANT The effect of the firewall catalytic converters is monitored based on the O 2 sensor signals downstream of TWC.

  Component description for O 2 sensors   GF07.04-P-6100BK 
  ME-SFI [ME] control unit, component description   GF07.61-P-6000BK 
  Component description for the engine diagnosis indicator lamp Except USA ONLY GF54.30-P-5010BK
  Component description for the "CHECK ENGINE" indicator lamp USA ONLY GF54.30-P-5011BK
  Fuel injection valves, component description   GF07.03-P-6010BK 
  Three-way catalytic converter, component description   GF49.10-P-2010BK