I had 2 OBD II codes come up with P0171 & P0174 that state system too lean (Bank 1 & 2). What is the most likely culprit for getting a code like this? I read on a search that MAF sensor could be dirty or not working? I have a 98 F150 with 112k with a 4.6L.

Has anyone had these 2 codes come up?
I would like to troubleshoot the most common reasons, and go from there.

 

MAF dirty. a vac. leak somewere past the MAF. bad or wrong spark plugs and bad o2's i think i coverd most of the things that could make it run lean....but not all of them...

 

I think its probably a dirty MAF sensor due to the hesitation at take off. It has been running poorly just as I accelerate from a stop, and previously thought that problem was my clutch which had just been rebuilt.

Thanks for the info.

 

The most common cause is actually a vacuum leak, specifically the PCV elbow behind the engine. LOTS of threads on this here.

 

X2.......If you use the search function on this site, you will probably find every answer you are looking for concerning these two codes. I have a detailed thread on this subject from a year ago. This is one of the most talked about CODE issues on this site.
Go to search (top black bar, 3rd from the right). type in P0171 and/or P0174 and put aside a few hours, because there is alot to read.


Good Luck with it.
TJK