great advice; thanks. Do you know what part I have to replace that is throwing that P1178 code?

 

while it could be an O2 sensor, you could also look for a dirty air filter, etc.

 

Thank you!

 

I get the P1178 every couple of months or so. The truck runs fine and passes inspections as long as it has run long enough after I reset the code. I believe it means that the ECU is saying that it is adding fuel to the mixture at the max amount compared to it's base fueling map. Which means I probably have a vacuum leak somewhere. I can't find a vacuum leak to save my life, and the code only pops up every couple of months, so I've just put up with it. I have cleaned the MAF and throttle body to no avail. If you guys do find a cause, I would be very interested. Cheers.