Lean code, don't believe it's a PCV leak
 

hey guys, i have a lean code for bank two, went into live data on my code reader and saw that while the O2 sensors on bank one fluctuate normally, bank two has the after cat sensor up pretty high and the front is going lower than it should, .030 ish when it is only supposed to go to .1. i replaced the rear sensor as the truck just hit 100,000 miles, the average lifespan of the O2 sensors and it was stuck, any ideas if the front sensor could be the problem? or should i check elsewhere? The truck only gets rough after it heats up and hasn't had any problems as long as I've had it.

You have either a vacuum leak or an exhaust leak before the upstream O2. Bank 2 is driver's side.

Confirm the code is P0174?

Hmmm...get some starting fluid and look for a leak. May be an exhaust leak but it should be easy to find if that is the case. Seafoam is great for finding a leak in the exhaust.

yeah it is P0174, searched for exhaust leaks and didn't find anything major, maybe a slight one at the joint after the intake manifold but it's barely enough to feel, cleaned off MAF and replaced both sensors on that side, I'll start looking for vacuum leaks. Thanks I'd rather not have to take it to a shop

You don't replace O2 sensors for lean or rich codes, they are doing their job right.

ANY exhaust leak before the front O2 *CAN* trip a lean code.

I realize that now, I was given bad advice before, Oh well i just have extras. I think i found a leak in the intake so I'm going to take it apart and replace the gaskets, if that doesn't work I'll look into the exhaust, I don't think it's leaking, i checked through it again and didn't feel anything coming off it until the muffler. I am going to put in a new exhaust kit, header on back but i want to get a decent one, may have to put other projects off if there actually is a leak i guess.

Oh, you have an intake leak? That will do it.

p0174 is usually/commonly the isolator bolts that attach the lower composite plenum to the aluminum intake base. Not a hard job if you have small hands, with large hands, it's still easier than a plug change on a 4.6 or 5.4 in these trucks.