snowbird

I've spent the better part of today trying to remove and replace my rear Oxygen Sensor on my 99 maxima. I know the process is pretty easy, I have an O2 sensor socket and the new part, but I can't get the old one off. I have been working at it all day and the nut is starting to get stripped. The old sensor seems to be really siezed up. I tried running the engine for a while to loosen it up and I even sprayed some wd40 on it to try and free it. The damn thing still wont budge.

Does anybody have any suggestions on how I might be able to get the sensor off?

The sensor is located behind the Catalytic Converter and right in front of another canister on about a 8 in piece of curved pipe. This piece of pipe is attached by just four bolts, 2 on each side, so my next step is to try and remove that then attempt to remove the O2 sensor. I might end up having to replace that whole piece. I really don't want to do that if I could just get the sensor off.

Does anyone know what to call the short piece of pipe that the sensor is installed in? just in case I have to replace it.

Any help on this would be appreciated and thanks in advance.

gabex

iTrader: (2)

Mine was stuck on their real bad. I just hammered at it...and hammered.. and finally I got some progress.

D1NOnly34

iTrader: (4)

Just curious, why are you changing it? Got a cel? Any symptons to your car due to the rear heated o2 sensor? Let me knwo thanks.

snowbird

Thanks for the tip. I was hammering at it as well today but I'll get after it again tomorrow. I'm just worried I'm going to strip the nut so bad I wont be able to get a grip on it. Oh well, I'll get that damn thing off some how.

I'm replacing it because I'm sick of looking at the check engine light. In fact, a friend of mine told me that when the CEL is on the car goes into a safe mode and doesn't perform at its best. In fact I notice that after I reset the ECU the car seems to be much more peppy. So I figured I would replace it now because I'll have to in a few months anyway, when I go to get the IM test for registration.

Anyways, thanks again for filling me in on what you went through to change yours. At least now I don't feel it is a lost cause just yet. Im going to bang the **** out of that thing tomorrow.

Dave Holmes

Use an actual penetrating fluid like PB Blaster or S'OK. WD-40 is a lubricant, NOT a penetrating fluid. Spray a real penetrating fluid around the threads, let it soak, then give it a try. Repeat if necessary. You can also try to use a breaker bar. If you don't have one, a short "cheater" pipe over a good wrench will work if you have the room (but be warned, if it is really on there, you may break something with the added leverage).

Dave

rmb

Soak it for a few hours in a penetrating fluid like Liquid Wrench or PB Blaster. Soak it when it's warm but not hot. Tap tap tap the old sensor with a small hammer with sharp, light hits while you're soaking it, this helps the fluid penetrate. It can take a few hours for it to work. Then try carefully wrenching it. If it unscrews at all, don't force it, spray some more and screw it back in.

If that doesn't work use a propane torch with a pencil flame tip (the small pointed blue flame). Try to heat the pipe, not the sensor. Most penetrating fluid burns, so keep that in mind. The metal around the o2 sensor will expand with the heat before the heat transfers to the sensor, in theory. One thing that always works is to heat the crap out of it and then apply dry ice (with gloves) to the sensor and cool it down. You can use regular water ice but it won't be as effective...

Keep in mind these things will destroy a good sensor so only use them for removal of dead ones. Also don't get anything on the new sensor. Make sure all the fluids are cleaned up before the new one goes in....


-RMB

snowbird

Thanks for all of the tips. I've been soaking the threads in liquid wrench most of the day and tapping at it with a hammer. It is still stuck on there and the problem now is that I have stripped the nut pretty good and cannot get a very good grip on it with the socket.

Any ideas on how I can overcome the semi-stripped sensor nut?

I'm soaking it as we speak and right now I'm trying to get the think loose enouph that I wont strip the nut anymore.

Also, any ideas on what to do if I can't get the thing out?.....Thanks Again.

snowbird

Whats the pipe called that exits from the catalytic converter into the middle muffler?

Is it the exhaust adapter? or B-pipe?

It is only about 6 inches long and has a small bend in it. This is the piece that has the hole for the oxygen sensor. I think my next step is to replace that piece.

rmb

Did you try the propane torch too? Some stuff you're not going to get out without one... You can buy one for less than $30 at most any hardware store...

-RMB

PedalKick

Get a bigass pipe wrench like you'd use for plumbing if there
is enough room. It will grip the nut enough to get it out. It
will really destroy the sensor though.

Midknight MAXX

iTrader: (1)

Vise grips my friend. I had the damndest time getting mine out but I got it. And if you were talking about that 6" section of pipe that connects the cat and the b-pipe it generally called the s-pipe cause of its shape.

95maxmadman

yeah and put a cheater bar on the vise grips or plumber wrench for leverage.
i haven't met a nut yet that couldn't be busted w/a cheater bar.
yeah they break but...

03G35

I had tough time taking my rear sensor off too, I tried all kinds of sprays and fluids but it didnt help, so I just heated it really good and it came off easy

snowbird

Thanks alot guys. I was going to just replace the S-pipe but I'll try the torch and vise grip idea. This has turned out to be the biggest b!tch ever.

gabex

iTrader: (2)

Just to let you know, I was having problems w/ getting my LF O2 sensor off the other day, so I tried PB Blaster as stated in this thread. WOW THAT **** IS GOOD. Got it off so much easier. Oh yeah, by the way ... be sure to check your part w/ the one you purchased. It sucks to get your old O2 sensor off then realize the dumbaszes at AutoZone/NAPA/Wherever gave you the wrong one (Yes this has happened to me 3 times now).

vmok

Also, you can try a flare nut wrench if it's not stripped too badly. It's a cross between a open end and a box end wrench. It has a slot cut in it to slip the wire through.

If you know anybody with an impact wrench, the tapping action of the immpact is sometimes all it takes to loosen frozen nuts/bolts.

-V

DR-Max

iTrader: (3)

Yeah, that PB Blaster is good stuff...well worth $4. It made my life a lot easier when I had to replace the 3rd and last O2 sensor on my Maxima. I sprayed it on the threaded body of the sensor and let it soak for about 10 minutes. Using an open wrench and using another open wrench as a cheater bar and it came right off w/o flack. I also sprayed it on the catalytic converter shield mounting bolts and they came off real easy.