I have the error code P0170 and have replaced the Mass Air Flow sensor 2 times, the first one was used thought it was bad so replaced with new, was off for one month. The light is back on and reads the same code. The car bogs down and has no get up and go. Any ideas?
Thanks

 

check the air mass sensor for oil contamination if it has oil on it clean out with brake cleaner make sure oil level is correct when engine warm it may also be necessary to clean excess oil out of intercooler and also clean carbon deposits from throttle body
on occasions the crank case ventilation tubes which go into cylinder can become blocked and may need cleaning
regards
conect

 

Dont know if it helps, but my dad has a 2000 ML320 and he was told that if he just changes the MAF that he will be doing it again in a month. The solution he was told was to change it and the cat convert at the same time. Make any sence? I happen to have the same prob you are having with my 2000 c230k.