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

ENGINES 272.920 in MODEL 203 up to Model Year 08 /Modification Year 07

ENGINES 272.922 in MODEL 211

ENGINES 272.940 in MODEL 203 up to Model Year 08 /Modification Year 07

ENGINES 272.941 in MODEL 203 up to Model Year 08 /Modification Year 07

ENGINES 272.942 in MODEL 171 up to Model Year 08 /Modification Year 07

ENGINES 272.943 in MODEL 211, 219

ENGINES 272.944 in MODEL 211

ENGINES 272.945 in MODEL 251 up to Model Year 08 /Modification Year 07

ENGINES 272.946 in MODEL 221 up to Model Year 08 /Modification Year 07

ENGINES 272.960 in MODEL 203 up to Model Year 08 /Modification Year 07

ENGINES 272.963 in MODEL 171 up to Model Year 08 /Modification Year 07

ENGINES 272.964 in MODEL 211, 219

ENGINES 272.965 in MODEL 221 up to Model Year 08 /Modification Year 07

ENGINES 272.966 in MODEL 230 up to Model Year 08 /Modification Year 07

ENGINES 272.967 in MODEL 164, 251 up to Model Year 08 /modification year 07

ENGINES 272.970 in MODEL 203 up to Model Year 08 /Modification Year 07

ENGINES 272.972 in MODEL 211

ENGINES 272.975 in MODEL 221 up to Model Year 08 /Modification Year 07

ENGINES 273.922 in MODEL 221 up to Model Year 08 /Modification Year 07

ENGINES 273.923 in MODEL 164 up to Model Year 08 /Modification Year 07

ENGINES 273.924 in MODEL 221 up to Model Year 08 /Modification Year 07

ENGINES 273.960 in MODEL 211, 219

ENGINES 273.961 in MODEL 216, 221 up to Model Year 08 /modification year 07

ENGINES 273.962 in MODEL 211

ENGINES 273.963 in MODEL 164, 251 up to Model Year 08 /modification year 07

ENGINES 273.965 in MODEL 230 up to Model Year 08 /Modification Year 07

ENGINES 273.967 in MODEL 209

ENGINES 273.968 in MODEL 221 up to Model Year 08 /Modification Year 07

ENGINES 272.940 in MODEL 209

ENGINES 272.960 in MODEL 209

Fig 1: ME-SFI Two-Sensor Control Function Diagram

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

The ME engine control unit determines the lambda mean value from signals from 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 O₂ 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 O₂ sensors downstream of 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.

The effect of the firewall catalytic converters is monitored based on the O₂ sensor signals downstream of TWC.

ME-SFI [ME] control unit, component description		GF07.61-P-6000V
Component description for O₂ sensors	O₂ sensors upstream of TWC	GF07.04-P-6100V
Component description for O₂ sensors	O₂ sensors downstream of TWC	GF07.04-P-6100VA
Three-way catalytic converter, component description		GF49.10-P-2010V
Component description for the "CHECK ENGINE" indicator lamp		GF54.30-P-5011V
Component description for the engine diagnosis indicator lamp	Except	GF54.30-P-5010V
Fuel injection valves, component description		GF07.03-P-6010V