My vehicle is a 2000 Ford F150 5.4L. AF1 3" and super 44. It threw codes back in december, 2 lean banks. Only happened during extremely cold weather. Cleaned maf sensor, BgK44 in tank, cleaned TB. Code was cleared and didn't come back on until now, on a very cold day. Only thing left is O2 sensor's or I have a serious problem. Isn't 140,000 alot for O2's?

Do you think these are the culprit?

 

O2's are not the culprit.

They are doing just what they are designed to do.

Take a grab at that PCV elbow/hose and check for cracks. Heck, just replace it.

The other thought that comes up often is intake manifold gaskets. Not sure how bad 2000 model Tritons were with those...

O2's last a lot longer than they used to, so I'd not worry.

I have the same P0171/0174 as well. I'll stop being lazy about pulling that hose eventually...

 

Alfred, you couldn't get away with it here in NY, because of the emissions testing. It would drive me nuts having that CEL on anyways

To the problem, replace the pcv assembly. I paid $28.00 for the entire assembly from my local Ford dealership last March. Took care of the problem along with cleaning the MAF really well.

My truck just passed 145,000 miles with the original O2's