BMW 3 (E46). Manual - part 21
Additional information, MIL:
A fault code is stored within the
ECM upon the first occurrence of
a fault in the system being
checked.
Two complete consecutive drive
cycles with the fault present
illuminate the MIL. The exception
to the two-fault requirement is a
catalyst damaging fault, which will
turn the light on immediately.
If the second drive cycle was not
complete and the specific function
was not checked as shown in the
example, the ECM counts the third
drive cycle as the next consecutive
drive cycle. The MIL is illuminated
if the function is checked and the
fault is still present.
Once the MIL is illuminated it will
remain illuminated unless the
specific function has been
checked without fault through
three complete consecutive drive
cycles.
The fault code will be cleared from
memory automatically if the
specific function is checked
through 40 consecutive drive
cycles without the fault being
detected.
Note:
In order to automatically clear a catalyst
damaging fault from memory, the
condition under which the fault occurred
must be evaluated for 80 consecutive
drive cycles without the fault
reoccurring.