I have a 2004 gmc sierra 2500 hd and my check engine light is on and I had hooked it to a test set and was told that all 4 of my o2 sensors were bad. Now I heard that all the sensors wont go bad at the same time and that it could be a vacum leak or a fuel pump issue. How true is that and what could it possibly be.
Apr 29, 2009 at 8:50 PM