FixVault

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

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

Fig 1: ME-SFI Two-Sensor Control Function Diagram
G07634028Courtesy of MERCEDES-BENZ USA

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.

IMPORTANT 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
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 USA ONLY GF54.30-P-5011V
Component description for the engine diagnosis indicator lamp Except USA ONLY GF54.30-P-5010V
Fuel injection valves, component description   GF07.03-P-6010V