My 2009 Hemi keeps giving me a check engine light. I checked the code with my Superchips tuner, and it's a P1129 - Closed Loop Fueling Not Achieved - Bank 2. Quick searches online point this as the code the truck gives if the fuel cap is missing. I haven't put a new fuel cap on yet, but I've checked that it's tight enough countless times. Plus, I turn it several clicks when put it back on after refueling.

This has been going on for a month at least now. The check engine light will stay on for a trip or two, or maybe a couple of days, but it'll eventually go back off on it's own. I'm starting to think it might be a pre or post cat O2 sensor issue. I found this thread on a 3rd Gen RAM that seems to had a similar issue: https://dodgeforum.com/forum/3rd-gen...installed.html

Has anyone else ran into this on a 4th Gen?

 

I have a 2012 and I am having the same issue. I changed my map sensor, air intake sensor, coil packs, spark plugs, and all 02 sensors, still same code. if you find a fix tag me in it please cause mine is a bit rough in idle and when moving from park to drive it sputters and gets really really low RPM like it wants to cut of but I tap the gas and it shoots back up to where it needs to be. light still on after a couple miles though