p0171 code

Just put on a k&n intake and now I’m throwing the po171 code, truck runs fine, any ideas?

The intake box in it before was cracked and so many hoses where cracked out and barely holding on, I think it was definitely taking in air before, is it possible that the computer learned the added air and didn’t throw a code, but now that I have all new hoses and new pcv valve and new intake that it’s not used to it?

 

Clean the MAF. The K&N would always cause me to get a Lean code because it would oil up the sensor. I’d have to clean it every two weeks or I’d keep getting a code.

Eventually I got tired of it, and got rid of the K&N.

 

Had this code thrown a couple years ago, I replaced the upstream o2 and the MAF and it cleared. Code got thrown again a couple days ago, cleaned the MAF, filter etc. and I’m still getting it thrown after clearing it. Anybody on here ever had it be the downstream sensor?

 

The downstream just monitor the cat.

 

I figured. Realized one of the intake hoses had popped off and the upstream sensor was thrashed. Replaced that yesterday and I’m still getting the code. The truck’s running fine (for now) and isn’t showing any signs of misfiring. Probably gonna go in for a vacuum leak test tomorrow. Any other ideas on what it could be?

 

It's been almost a year since your last post.
Were you able to resolve your issue?

 

Hey, wanna see what you guys think of my issue P0171 issue. I'm running out of diagnostic ideas. (2000/ 3.4L/ 5VZ-FE/ 4WD/ Auto) Looked up multiple threads and youtube and they all point to the issues below.

I recently replaced my valve cover gaskets and after that it started to throw a P0171 code. I've seen this code in the past a few times and was remedied by cleaning the MAF or replacing the O2 sensors. Things I've tried this time:
-Cleaned the MAF, pulled neg terminal Light came back.
-Replaced the MAF, since its 22 years old. Light came back.
-New air intake hose, new hose from air box to evap canister, new hose from intake silencer to manifold(?)plenum(?)

Haven't yet replaced the fore O2 sensor yet, just waiting for it to stop snowing for a bit here in UT.

Any other thoughts on what I can check? TIA.