Thread: Both O2 Sensors Bad? What? I Call BS

2000 GT
157,000mi
Open cone filter thats it.



So I have had a check engine light on for a while now because of a bad MAF sensor. I took it to Orielys after I replaced the maf because the Check engine light came back on. I just had a power steering pump line replaced and then the oil sending unit I guess. Codes that were thrown were P0102 again which is the MAF circut low input which I have reason to believe is due to the open cone filter so Im not too concerned with that. The other codes were a P0131 which is an O2 Circut Low Voltage Bank 1 Sensor 1 and a P0137 O2 Circut Low Voltage Bank 1 Sensor 2. I find it hard to believe that both would decide to crap out at the same time like this. My only thought is that the cat is the culprit?

My thought is you don't realize the maf 5volt is likely the same as the O2's. Unplug the maf, clear codes then drive and see if the O2 codes come back. If not, Maf is the issue.

I looked this up yesterday, check fuse 21

Didnt know that it was the same. Yesterday after I checked the codes I cleared them and drove around town perfectly fine. When I got out in the country I did a WOT run up to about 60 and it came back on. I forgot to mention that part. Thats part of the reason I thought maybe restricted flow was the issue.

Originally Posted by bigburban

I looked this up yesterday, check fuse 21

I had checked fuse 21 about a month ago when I was having more MAF issues and it was fine. Probably wouldnt hurt to check again though.

You went wot, the maf got cooled by the air, which meant that circuit pulled more power and poof, your craptastic maf blew the fuse.

That's a theory.

Cause you know that the maf reads by how much electricity it takes to heat that little wire right?

Ahhhh. Yea I thought the MAF dealt with electricity but to be honest I wasnt sure how exactly that all came into play. The first MAF I got wasnt what I thought it was and so that gave me problems so I got a used one from Morad so I would think I wouldnt have any issues? I dont know. Is it because its winter and Im not using the stock air box that would cause too much cold air in? Should I just swap the intake out for stock and see if I dont have anymore issues?

maybe you have some rubbed wiring.

Okay. Ill poke around and see what I can find. Thanks!

It's about time to get a new cat. They last about 150k. Even if it's not the issue, it will be soon.

Cat's don't clog just to clog though. I've seen stockers with 200K on them.

Plus..if the voltage is low, and we are talking mV the o2 is reading, that would be lean. Cat's typically clog from a failed o2 which is super rich.

Yeah, I agree that something electrical is up, but think it's always a good idea to mind the cat.