- Joined
- Sep 28, 2002
- Messages
- 39,799
I got the guinea pig back. The wrench did an emissions test/inspection on it since it was due. Needed an O2 sensor. It passed, as always. I do an on board diagnostic a few days later and I get a bad MAP code and a "O2 always reads low voltage" code. I read that the low voltage can be because of a whacky MAP sensor in the notes on allpar....so I swap out the MAP ...disconnect the battery ..run it a while ...no codes. Feel all warm and fuzzy. Go and get gas (6 miles = $0.20 cheaper
) ..have to wait in line (because it's $0.20 cheaper
) ..so I do another diagnostic (turning the key on-off-on-off-on and read the flashes on the CEL) ...O2 always reads LOW. So, just in case the wrench put in a defective O2 ..I put a new O2 in (I would get $$ back from him if it was indeed defective) ..same deal ..no code ...after a longer drive same code.
Now I'm stumped of where to look next. Some suggested that a vacuum leak will make the O2 to low voltage ..but I would assume that low is "lean" and one would think that the MAP would be effected and read it as a wider throttle and the PCM should act accordingly. I reason that a manifold leak won't be interpretted any differently than a throttle opening.
Any ideas?
![shocked.gif](https://bobistheoilguy.com/forums/images/icons/shocked.gif)
![shocked.gif](https://bobistheoilguy.com/forums/images/icons/shocked.gif)
Now I'm stumped of where to look next. Some suggested that a vacuum leak will make the O2 to low voltage ..but I would assume that low is "lean" and one would think that the MAP would be effected and read it as a wider throttle and the PCM should act accordingly. I reason that a manifold leak won't be interpretted any differently than a throttle opening.
Any ideas?