I just bought a 2000 4.7 quadcab 4x4 w/4.7 auto. This code keeps comming up after the new o2 sensers and looking at all of the vac lines.Changed the plugs and oil . just can figure this one out. Please give me some input on what to look for next. Also the cat smells like crap but its not rattling.
Thanks in advance.
Chris

 

P0171 (M) 1/1 Fuel System Lean A lean air/fuel mixture has been indicated by an abnormally rich correction factor.

 

Check all of your vacuum lines to make sure they are connected correctly and that they are in good shape. Also, make sure you don't have an exhaust leak before that sensor. Another thing to look at is possibly the PCV valve sticking. Check all of that out and let us know if you find anything.

Oh, how did you connect the new O2 sensor? If you had to splice it in then you probably created too much resistance for it. OEM is the best way to go so that you can just plug it back in.

 

O2 were oem style from stealer.

 

Well did all of that and it still comes on. Running out of ideas. Please help me out.