ME-SFI two-sensor control, function - GF07.61-P-3020MIG
ENGINE 272.945 in MODEL 251.054/154 as of Model Year 2009/AEJ 08
ENGINE 272.967 in MODEL 164.186 as of Model Year 2009/AEJ 08 MOPF
ENGINE 272.967 in MODEL 251.056/065/156/165 as of Model Year 2009/AEJ 08
ENGINE 273.923 in MODEL 164.871 as of Model Year 2009/AEJ 08
ENGINE 273.963 in MODEL 164.172 as of Model Year 2009/AEJ 08 MOPF
ENGINE 273.963 in MODEL 164.886, 251.072/172 as of Model Year 2009/AEJ 08
Function requirements for two-sensor control, general points
- Circuit 87M ON (engine control ON)
- Engine running
- Operating temperature of firewall catalytic converters is reached
- Lambda regulation active
- Left and right O2 sensors downstream of CAT (G3/5, G3/6) defect-free
Two-sensor control, general points
The two-sensor control is used to monitor the function of the LH and RH O2 sensors upstream of the catalytic converter (G3/3, G3/4) and the effectiveness of the firewall catalytic converter.
To do this, the ME-SFI control unit (N3/10) reads the following sensors:
- LH and RH O2 sensors upstream of CAT, oxygen sensor signals upstream of CAT (catalytic converter)
- LH and RH O2 sensors downstream of CAT, oxygen sensor signals downstream of CAT
Two-sensor control function sequence
The ME-SFI control unit determines the lambda mean value using the signals from the oxygen sensors downstream of the catalytic converter. 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 value is determined for the lambda control.
The correction value (value with new LH and RH O2 sensors upstream of the CAT is about 0) is used to compensate for aging of the O2 sensors upstream of CAT, within certain limits.
If the correction value exceeds the specified limit value, the O2 sensors upstream of CAT must be replaced.
The correction value depends on the performance map, and is applied by the ME-SFI control unit by adapting the injection time of the fuel injection valves (Y62).
If the specified limit value is exceeded, or the plausibility check on the oxygen sensor signals (upstream or downstream of CAT) is negative, the ME-SFI control unit actuates the engine diagnosis indicator lamp on the instrument cluster (A1) (A1e58) (or with code (494) USA version, the CHECK ENGINE indicator lamp (A1e26)) over the engine compartment CAN (CAN C).
The exceeded limit value is stored in the fault memory of the ME-SFI control unit and can be read out and deleted using the Diagnosis Assistance System (DAS) system.
| Electrical function schematic, two-sensor control ME | Model 164 | PE07.61-P-2763-97MAA | ||
| Model 251 | PE07.61-P-2763-97RAA | |||
| ME-SFI [ME] control unit, component description | N3/10 | Engine 272 | GF07.61-P-6000MIG | |
| N3/10 | Engine 273 | GF07.61-P-6000MLG | ||