okay i have a question about my 2009 duramax lmm i started it up one morning and let it warm up and im in my garage and i hear it rev up and start knocking the truck had been acting like it had a dead batteries a few days leading up to this so i started driving it down the road it had a check engine light on it wouldnt go over 1k rpms so i had it towed to the dealership they said it was a code p0191 and that it could have cuz one of my battery cables was loose so ive had it home for a couple weeks and it doesnt seem to be running exactly right i was going up a hill and i was getting on it pretty good and then i let off the gas and it seems to be starved for fuel it just doesnt seem to be running exactly right like it should have more power i was wondering if the dealership just erased the code and sent me on my way i was looking at the code on the internet and it says it has to do with fuel rail pressure i was wondering how to figure out exactly whats going on? im gonna try getting a new fuel filter tomorow and see if the helps at all anybody have any input or the same problem id appreciate it thanks

 

Could be the fuel pressure sensor going bad

 

I was thinking that but does anyone know exactly how I would find out how to pin point the problem thanks