[motorsports12]

i have a 2012 gmc sierra 2500hd wt with the 6.0l gas engine (flex fuel) that just turned 100,000 miles - it has been really cold weather off and on so not sure that has much to do with this but a week ago the check engine light came on - put it on the obd scanner and got code p0171 and p0174 both banks running lean - one of the fixes was to clean the maf sensor - so i did - and for a week the problem went away - thought it was fixed but it came back on - i just put gas in it this evening and thought i would wipe the ring off where the gas cap seals - the check engine light went off again

could it be i have a bad gas cap or a bad seal at the gas cap - is the maf sensor bad - do i have some other issues like an o2 sensor going bad or maybe a vacuum leak - the only thing i have done to this truck (only had it for 6 months) is change the oil and the air filter and just recently had to change both head lights (reason i bring this up is because i had to remove the air box on the passenger side (could there be an issue there since its hard to get the box back into its rubber push grommets) and a battery tray on the drivers side

not sure my problem is fixed but wasnt sure if i should try anything else - i use this truck to pull a trailer to and from the race track so i need to make sure its good for the season with racing season about to start