I am attempting to install an aftermarket cat. on my 2002 O-Z Lancer and am having trouble removing the oxygen sensor from the factory Cat. I was wondering if anyone knows whether the sensor simply unscrews with a wrench as it would appear, or if the wire that runs from the sensor into a rubber grommet on the underside of the car is able to be detached, which would make the unscrewing easier than having to do it while under the car. Any help would be greatly appreciated.

 

get an o2 sensor nut,,,it should take care of it

 

They actually make a tool-like socket to remove it easily.

 

I have heard of this tool, which I can see working on the sensor coming off the engine because I can unplug it from it's harness, but the one under the car on the cat. converter doesn't seem to be able to unplug, I could be wrong on that account or the tool may get around the wire with it still being attached. I appreciate the info though and will have to check this tool out.

 

Thanks for the info, I think I'll just have to take my *** down to Auto-Zone and find the right tool for the job, need any blinker fluid while I'm there?

 

My preference for removing the o2 sensor is a 7/8" line wrench. it looks like a box wrench, but it has teeth on the end. I also spray the hell out of it with P'Blaster.... it's in a yellow can at your parts store. if you don't find it on the chemicals/degreaser aisle, ask for blaster penetrating spray. Anyway, spray the heck out of it. slide the line wrench onto the o2 sensor then use a cheater bar or a rubber mallet on the wrench to convince the o2 sensor to come off. It's just heat-rusted in place and will come out with enough trying....
If you're REALLY bad off, use a propane torch to heat the bung that holds the o2 sensor and then use the wrench- be careful fire is hot and can burn things!

I tried the "proper" tool, the sensor socket and it all but stripped the nut on the sensor, I won't use that tool again.

Good luck

 

Good deal, thanks for the detailed info engineerboy. Now as soon as the snow gets off the ground here I'll work on the damn thing. lol

 

I just used a wrench; not sure what size but the ]==O kind; just use the closed end and apply ALOT of torque; i also doused (sp?) it in wd40. It will come off but use the closed end so you dont strip it; mine is barely alive after the hell i put it through.
-Heath

 

1. 2-3 hours before you start working on the bolts, put some LooseNut (made by Gunk)
2. Put some more every 30 minutes.
3. When you feel it's time, or when you can't wait anymore, grab a pair of vise-grip(ther big ones, not the nose picking crap) and clamp it on the o2 sensor(clamp it as tight as possible to avoid stripping).
4. Once the vise-grip is clamped real good, break loose the bolt.

If you're still not able to take it off. As Engineerboy said:

1. Blow torch the hell out of it
2. Slap the vise-grip on(do I need to say what kind of vise-grip )
3. Break it loose

Still not able to do it?
1. Take your car to the nearest garage, ask them to break loose the bolts(should cost you 1/2 hour worth of labor)
2. Bring the car back to your place and install your stuff

 

kelspar.... how'd you get the wire through the closed end of the wrench

I'd be afraid of stripping the bolt with vicegrips..... the linewrench is cheaper anyhow

 

I was too... It's not garanteed not to strip, but that's how I did my past 3 o2 sensor

 

you can unplug the wire from the passenger side, real close to the center console. you have to pop off the little plastic kick panel and pull up the carpet. the grommet pops right out to the underside of the car and pops right back in with no problem.

 

i used a O2 sensor socket to try and remove my sensor on my cat, but it stripped the **** out of it, and a torch was needed to be used. Came off well with the torch.

 

I knew about the O2 sensor coming out.... didn't think the rubber boot came off that easily, though. Good info.... but it sounds like a lot more work Besides, I needed the wrench for other projects, so it's come in handy.

 

when i did my cat.. i actually took off the whole cat... i cut the wires! lol... and then soder iorned it back and wrapped it in electrical tape