2007 Suburban, 5.3 don't know if it's LMG or LC9 161,496 on the clock. Time to time after running on regular gas check engine light comes on then fill up on BP premium (specifically BP I don't know why) a couple tanks and light goes off then start this cycle all over. This is my sisters truck so I'm kinda at arms length here, what could cause this? TIA

 

Well, what trouble codes are popping up? Could be coincidental or could be the cats. My CEL would come on more often for the cats when running E85 compared to gasoline.

 

Thanks Swath, havn't searched for codes- everytime I'm there I don't have my computer she's in a few states over. I'll scan next time I'm up there, or I guess if it gets bad enough direct her to an Autozone………….

 

 

Richard

 

 

It could also be an intermittent code entirely unrelated to gasoline type. Hard to tell until you actually pull the code. Autozone is quick and easy. Direct her there.

 

Yeah, getting down to that, I just thought with that kind of mileage that combustion chamber could be garbaged up or something like that...……..