This is a common problem, and the answer applies to most OBD II vehicle.
Since your BMW was recently repaired it appears the emissions monitors were
erased from the OBD II computer. Setting the emission monitors requires
driving your car at least 200 miles, consisting of everyday normal driving,
stop and starts (like at red lights and traffic), ignition on and off
several times a day with at least 15 minute pauses in between (this allows
the EVAP monitor to run), and freeway driving at least on three occasions
for at least 15 minutes each at speeds above 30 mph. After these driving
conditions are met and your BMW still fails the OBD II portion of the smog
check, we can only recommend a smog check repair center conduct a diagnosis
of the OBD II computer as to clues of why the monitors are not setting.
Assuming no Check Engine light or Malfunction Indicator Lamp is illuminated
we have to suspect your vehicle's only problem is simply not enough drive
time yet.
posted by SmogTips Support