[whoareyou4]

I own a 2001 Cat and have has issue's with codes P0171 and P0174. I have read all the posts on here regarding what may or may not cause the codes.

I found a vacum leak and fix that, reset the computer and the codes came back.

At pretty much the same time I replaced the fuel filter, removed the MAF and cleaned it( I wanted to try cleaning it first before shelling out the $127), and tried a full tank of Non-oxy premium fuel.

The codes hav not come back, I switched to to the no-oxy fuel oned day before doing the other stuff and the CEL did not come back on, where at other times I reset the CEL the light came back on very soon after.


So I am thinking that the Premium non-oxy fuel may have had something to do with it.

Regardless of your thoughts on ethanol, has anyone had poor luck running in their Cat's, i.e. has it seemed to cause the CEL light to come on?

Don