I had gotten code 28 two times now. The CEL hasnt turned back on since then, but i have noticed that my gas mileage is rediculously HORRIBILE. Im thining mayve o2 sensor? Ive searched all over to find what code 28 is, but no success. Someone please help me. Thanks.

PJ

 

That would be the Rear main O2 sensor. Good guess with the O2 sensor

 

Awesome thanks for the quick response. Now the newb question. Which one exactly is the rear main one? one of the ones on the mani or the one after the cat?

 

which one is the rear main one? one of the ones on the mani or the one after the cat? I need to make sure to order the right o2 sensor. thanks PJ