P0171 -p0174 BMW -

Question

hi
2001 bmw 325i
when i replace the new mas air flow i got 2 codes p0171-p0174 with unready item's like catalyst and o2
when i put the old mas airflow the obd show just this code p0102

Answer 1

P0102 MAF circuit low input

The MAF that set P0102 is definetly non operational. When you install the other and get P0174 and P0171 these are lean Bank codes. This can another faulty sensor, What can set lean code and gets missed on BMW are leaks that can come from faulty oil caps, even the valve cover gasket. Try another MAF if the lean code are there there is a vacuum leak somewhere.