GF07.61-P-2004KE Diagnosis Fault Memory, ME-SFI Function

GF07.61-P-2004KE Diagnosis Fault Memory, ME-SFI Function
- up to model year 08

Component Identification:

The ME-SFI [ME] control unit checks its input and output signals for plausibility and recognizes possible faults. The detection of faults and their storage is differentiated in:
^ Faults constantly present
^ Loose contact fault (only on coolant temperature sensor (B11/4) and accelerator pedal sensor (B37))

The following components and systems are monitored:
^ Oxygen sensors
^ Catalytic converters
^ TWC heater
^ Secondary air injection
^ Smooth running control (combustion misfire)
^ Fuel system
^ Control units (which are linked via the data bus)

Driving cycle
Systems that are not constantly monitored are checked only when a driving cycle is executed.

A driving cycle for a test consists of:
^ Engine start (cold start)
^ City cycle
^ Outer city cycle
^ Engine switch-off

As the required operating conditions are not always given, all the tests are also not completed in one drive.

Fault recognition
The following faults and error states are detected:
^ Signals above or below the limit value (open circuits, short circuits, faulty sensor)
^ Frequency of fault
^ Illogical combination of signals
^ Function chains with faults
^ Fault messages of all systems transmitted via CAN data bus (control units)
^ Fault states from the alternator (G2) with interface controller

Engine diagnosis indicator lamp (except United States of America)
If an exhaust-related fault occurs in two consecutive driving cycles, the engine diagnosis indicator lamp in the instrument cluster.
In the event of a fault which could damage the catalytic converter, the engine diagnosis indicator lamp flashes.

The indicator lamp goes out after 3 correct, successive driving cycles.

CHECK ENGINE indicator lamp (ON United States of America)
If an exhaust gas relevant error occurs or if it was already stored in the last driving cycle, the CHECK ENGINE indicator lamp lights up in the instrument cluster.
In the event of a fault which could damage the catalytic converter, the engine diagnosis indicator lamp flashes.

The indicator lamp goes out after 3 correct, successive driving cycles.

Fault storage
Faults detected are stored in the fault memory as a fault together with freeze frame data. If the fault is not confirmed during the following driving cycle, it is deleted. Emission-relevant faults are always entered, they have a high priority.

After 40 correct driving cycles, an exhaust gas relevant fault and after 80 correct driving cycles, a TWC damaging fault is erased from the fault memory.

Read out the fault memory
The ME-SFI [ME] control unit is connected via a serial interface (K- line) to the data link connector. The stored faults can be read out and deleted with STAR DIAGNOSIS or with a standard output device (generic scan tool) with "Ignition ON" or with the engine running via the data link connector (SAE standard ISO 9141-2).

The fault memory is not erased if the vehicle battery is disconnected.

Fault freeze frame data/operating conditions
If a fault is detected, the following data are stored:
^ Fault code
^ Vehicle speed
^ Engine speed
^ Coolant temperature
^ Air mass
^ Engine load status
^ Throttle valve angle
^ Ignition angle
^ Selected gear (with transmission 722)
^ Mixture formation adaptation value
^ Lambda control status (enabled, not enabled, locked during fuel shutoff, locked during fault detection, without correction of O2 sensor downstream TWC (G3/1))
^ Environmental conditions (e.g. fuel tank level, distance in the case of fault entry, counter readings for fault frequency, purge system or air injection system active)
^ Alternator voltage (with alternator with interface controller)

Function chains are test sequences, e.g. for air injection, purge system and leak-tightness of fuel evaporation control system (for United States of America), activated by the ME control unit.

Consequential faults
If a faulty signal is detected and the corresponding fault code is stored, all the tests in which the signal is required as a comparative parameter are aborted. This ensures that no consequential faults are stored.

Readiness code
This code makes it possible to recognize that tests relating to fault recognition are in progress and the system is thus active.
recognition are in progress and the system is thus active. The code is set once the following tests are completed (result of test not significant):
^ Catalytic converter effect
^ Purge control
^ Secondary air injection
^ O2 sensor signal and O2 sensor heater upstream if TWC

Emergency running
If a fault is detected, substitute values are formed for the emergency running and the engine diagnosis/CHECK ENGINE indicator lamp lights up.

ME-SFI [ME] control unit run-on
After faults are erased it is necessary to wait until the processor has completed its power-down sequence after the ignition is switched off. The duration is adaptable (programmable) and is about 5 s.