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Home >> Mercedes Benz >> 2007 >> ML63 >> Repair and Diagnosis (Single Page) >> Engine Performance >> Ignition System >> Fuel, Ignition, Engine Control - Basic Knowledge - 2 Of 2 -- 164 Chassis >> Basic Knowledge >> ME-SFI two-sensor control, function - GF07.61-P-3020 >> ME-SFI two-sensor control - function - GF07.61-P-3020BK

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

ENGINE 113.967 in MODEL 219 

ENGINE 113.964 in MODEL 164.1 

ENGINE 113.971 in MODEL 251 

Shows model 219 

Fig 1: ME-SFI Two-Sensor Control - Function Diagram
G05257589Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

The ME engine control unit determines the lambda mean value from the signals of the O2 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 O2 sensor upstream TWC approx. 0) makes it possible to compensate for aging of the O2 sensor upstream of TWC within certain limits. If the correction variable exceeds the limit value, the oxygen sensor upstream of the 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 enable when the catalytic convertors have reached their operating temperature and the O2 sensors downstream TWC are correct.

If the limit values are exceeded or the plausibility check of the O2 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 three-way catalytic converter is monitored by means of the O2 sensor signals downstream of the TWC.

  Component description for the O2 sensor   GF07.04-P-6100BK
  Component description for the engine electronics control unit   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" MIL USA ONLY GF54.30-P-5011BK
  Component description for the fuel injection valves   GF07.03-P-6010BK
  Component description for the three-way catalytic converter   GF49.10-P-2010BK