Help codes p0171 and p0172 Fuel Trim Malfunction

Discussion in 'SN95 4.6L Mustang Tech' started by v8carnut, Nov 12, 2005.

  1. Check engine light came on. I pulled the codes and get p0171 and p0172 Fuel Trim Malfunction. It starts and runs rough at idle and misses at about 1200 RPM. Any ideas??
  2. p0171 is system lean and 0172 is system too rich, maybe a set of 02 sensors that are shot and sending the computer bad signals
  3. The codes are kinda vague I’ll change the o2’s I’m sure they could use it anyway. Thanks!
  4. OK I’m stupid I found the culprit , frick’n vacuum line… plugged it back in and she’s running sweat again.. and I dnd’t spend any money either.. Yee Haa :banana: