I have a 97 f150 4.2L 4x4 and I keep getting a po141 code. I have replaced the downstream o2 sensor twice on bank one. But the code keeps coming back up. Any help please.

With a scan tool check the other o2 sensors, they sould lead the sensor behind the cat, between .1 -.9v .

I am not certain of the code but if I am not mistaken, that could be the sensor for the Cats, meaning you may have innsuficiant Cat quality. Which all that means is you are polluting to much and your CEL will be on in the dash. Replacing a cat is too expensive.

I agree, if the sensors are working then its probably the cat

I had an O2 sensor code, and I believe it was the P141: 1st Bank Lean.
I'm pretty sure, anyway.
It ended up being exhaust leaks between the downpipes and the maniofolds.

I may be kickin' dandelions in left field, but I thought I'd throw in my two bits.

Miles

hi guys! new to board and I'm going to jump right in ! I had a97 5.4 that continued to show this code and if you check out the pcv hose behind the throttle body ,you might find the rubber nipple from the intake to the pcv hard hose either melted inside or cracked on the outside and this causes a lean code to show up!!! the pcv hose comes complete from Ford with pcv valve, hard hose and rubber nipple . the price was around $24.00 , much cheaper fix than o2 sensor!!! I found out the hard way by replacing the sensor first!! hope this helps!
2 Dawgs

I had the lean coads for banks 1 and 2 as well. Finally for this melted tube replaced it and POW the engine runs smooth.

I had lean codes on my 98 with 4.6, replaced the O2 sensors and a fuel pressure sensor only to have the code still come on. Turned out it was the MAF sensor, once that was replaced all was good and have not had a problem for months