I started my 92 4runner this week and I noticed it was loud. I look underneath for an exhaust leak but what I found was a wire hanging and my O2 sensor was GONE!

My questions:

Is it possible for two nuts and a plug to come loose and the O2 sensor to fall out?

This seems very unlikely especially because when I parked it the truck was fine, no check engine light, and no loud exhaust. I didn't notice the O2 sensor laying in the parking lot.

My theory is that someone took it. I have heard of cats being stolen for the scrap value, but has anyone had an O2 sensor stolen?

A few people live near me that also drive 4runners so I am hoping someone on here can explain this or else I will be walking the neighborhood looking for newly installed O2 sensors or fresh safety stickers.

 

well i got got a replacment for 200 bucks so it would be worth it to a crack head.

 

yeah, it's possible for two nuts and an O2 sensor to fall out.
is it possible for that to happen while the truck sits still while the driver sleeps?
yes...
...if someone loosens the nuts and pulls the sensor out.

 

I had a bolt work itself out of my brake caliper..the other almost came out too. Made a cool noise rubbing on the inside of the wheel.

Might have had something to do with the absence of Loctite though...

 

I've had trucks come in with both nuts missing, and the O2 hanging. It's possible that it just fell out (especially if the connector wasn't originally plugged in tightly).

In reality though... it's pretty rare.

 

mine did the same thing but the connector didn't fail. I started the truck and it seemed loud, I thought exaust leak so I look under and there is my o2 sensor hanging there, both nuts had come off. But if it came out and fell off while driving you would hear it right away. So yours was probably stolen.

 

DITTO. this just happened to me. On my way from San Antonio to Houston and some where during that trip I turned the AC and music down to make a call and noticed my truck sounded like a tank. Pulled over and sure enough, my o2 was hanging by the wire out of its spot. No wonder my feet were getting hot, that port is almost right under where the gas pedal is.

Easy fix thankfully. Bought the last 2 nuts the closest yota dealer had and fixed it right up. SO, I guess after almost 20 years of bouncing around, the fell off.

 

oh also. it didnt ping a check light. Suppose it only does a circuit check to see if it is attached, not that its actually in the right spot.. doing its job.