O2 sensor came loose and popped out of exhaust? wtf?!

I thought i had a hole forming in my muffler or something, got real loud. Got under there to look, and find my post-cat O2 sensor hanging by it's harness. The bolts (rusted???) off and the freakin sensor just popped out. How the hell could this have happened??? I'm glad it didn't fall off.

 

Just a guess, but since you live in NY you probably got salt or something on it year after year and it corroded...also, not sure if you're the original owner, maybe it's an aftermarket sensor?

 

Happened to mine too - just rusted bad and there it went.

Not an issue anymore though - put on new cats/muffler.

 

same thing on my "95". just the nuts rusted off, and not the studs. 2 new nuts and all was well.

 

also happened to me about two years ago, put on some new nuts and it has been fine since.

 

damn I'm glad I live in FL...

 

damn i'm glad I live in California!!!!!

 

wow, yea, almost hard to believe that the nuts could completely dissinigrate, and the whole senor could just vibrate right off of the studs. lol. I feel those things are hard to get off when you're trying to, who knew it could just come free. Glad I'm not the only one.

 

Kept hearing some clanging around down there and keep having the CEL come on and go off repeatedly so i decided to take a look and it didn't take long to figure out what was going on.

 

shit I think I'v just discovered that my nuts have rusted away too!! sensor is still in there solid as can be though, but the gasket is rotting away!! is there a trick to removing the sensor so that I can replace the gasket and the nuts?

 

Penetrant and vise grips. Use the penetrant for several days in advance, applying to hot exhaust and letting it work its way in while it's cooling down. If you still have the "sheild" some people have in their pictures on the rear one, you may have to cut it loose to get to the nuts with the vise-grips. You may also (or instead) want a nut-splitter or a dremel with a cutoff wheel to soften up what's left of the nuts.

Spend the $50 on a new sensor as well, IMHO. And the $100 up front (A/F) if that's not been done in your memory or 100K miles.

Stainless steel nuts, lockwashers (I couldn't find decent stainless ones, so I used non-stainless for those) and anti-sieze on the threads after you put the sensor on but before you put the nuts on.