How to Remove O2 Sensor

[lazabby]

Anyone have any tips on removing the O2 sensor? I've been put penetrating oil on the nut for a couple of days. The space is limited in the area so it's hard to get leverage. I'm using a 22mm wrench with no success.

[DMC5180]

Put the box end of the wrench on it and smack the other end of the wrench with a fair sized hammer. That should crack it loose. Your fallback would be heating the manifold with torch.


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[David T]

Penetrating oil, Liquid Wrench, etc, do not seem to work well on exhaust stuff. The only thing that REALLY works is an acetylene torch. Heat till cherry red, let cool and then heat just up to cherry again. Loosen before it cools much. When installing the new one use a drop of Never-Seize. Do not let any get on the probe end.
David Teitelbaum

[Dangermouse]

I managed to get a short length of pipe on the other end of my wrench, but I still needed a smack with a hammer.

Brush up on your swearing too as you go ;)

[lazabby]

I managed to get a short length of pipe on the other end of my wrench, but I still needed a smack with a hammer.

Brush up on your swearing too as you go ;)

Have any extra words I can use?

[lazabby]

Put the box end of the wrench on it and smack the other end of the wrench with a fair sized hammer. That should crack it loose. Your fallback would be heating the manifold with torch.



There is no room for a hammer. I did try putting a board from above through the engine to rest on top of the wrench. Then I whacked from above. It still wouldn't move.

[dvonk]

Brush up on your swearing too as you go ;)

i often find this this to be the best tool. :swear1:

:lol:

[Bitsyncmaster]

Mine came out with an open end wrench but autozone has some nice sensor sockets I've used on my other cars that work well. Sometimes a socket will work which lets you get a breaker bar on it.

[Dangermouse]

There is no room for a hammer. I did try putting a board from above through the engine to rest on top of the wrench. Then I whacked from above. It still wouldn't move.

Ah,

I did mine from below, with the car on ramps. maybe I have a longer wrench?

This is a family website, so you'll just have to be inventive with your cussing.

[David T]

If you don't use heat and it takes a lot of force you are best off with either a socket (cut the wire if you have to) or a box wrench that can go around the hex. If you have to use a lot of force, especially with an open end wrench or an adjustable wrench, you risk rounding the hex and slipping off. Better to use a pipe wrench or a vise grip. There is not a lot of room to swing a hammer and you wind up hurting yourself or bouncing the hammer off the most expensive parts nearby. BTW the bigger the hammer the more likely it will find the most expensive part to bounce off of. Hammering is usually a last choice kind of option. Once you start using heat to loosen things up you will always try to do it that way instead of brute force. I have had instances where the O2 sensor came out VERY easily, almost as if it was just hand-tight. Not very often though. Usually, because of the heat cycles, you have to fight them out. Another point, when you force them out without heat you risk ripping the threads out in the bung and now you can't screw the new one in tight. Remember to adjust the valves and reset the Lambda counter.
David Teitelbaum

[DMCMW Dave]

Get a torch. If you don't have one or are afraid of it find someone who does. Any muffler shop can do this, remarkably cheaply.

I've seen people keep beating in it cold and twist the end right off the O2 sensor. That makes for a Really Bad Day. Now you have a hole in the pipe and the threaded end of the sensor is still frozen in there. So then you remove the crossover for access (and if you don't have a torch you'll break the studs off the manifolds). It gets worse from there.

Even if you have to pay someone $50 (which would be a lot) to get it out, pay it.

[mluder]

Remember to adjust the valves and reset the Lambda counter.
David Teitelbaum

David,

I'm planning on replacing my Lambda this weekend... What valve adjustment are you talking about? I just assumed I would plug it in and go.

Steven

[Rich]

Get a torch. If you don't have one or are afraid of it find someone who does. Any muffler shop can do this, remarkably cheaply.

I've seen people keep beating in it cold and twist the end right off the O2 sensor. That makes for a Really Bad Day. Now you have a hole in the pipe and the threaded end of the sensor is still frozen in there. So then you remove the crossover for access (and if you don't have a torch you'll break the studs off the manifolds). It gets worse from there.

Even if you have to pay someone $50 (which would be a lot) to get it out, pay it.

+1 on this advice. These things are NOT like sparkplugs no matter how much they may resemble them.

Also, a note to all who have other cars with oxygen sensors that are over 10 years old and may need replacement one day - those sensors may be just as hard to remove. Car manufacturers apparently do not install exhaust sensors with anti-seize compound so all of this sensor removal advice applies; as you may guess, there's nothing peculiar about D's in this respect.

Be happy that this car has only one of them!

[DMCMW Dave]

Be happy that this car has only one of them!

And that it's only $22.

Price one (there are 4) for a modern BMW sometime. . . .

[nofear365]

My Eldorado ETC had 4 as well. OUCH!

[thirdmanj]

Have any extra words I can use?

I've found "Fluxing piece of Biff" gets the job done.

[lazabby]

O2 sensor was removed by the fifth person to try it. He was able to get a good grip with vide grips and put his weight in it. The car was not on a lift so I imagine he lifted himself pulling on the sensor. I had been putting penetrating oil on it for several days so that may have helped.

Anyone want to buy a used O2 sensor, slightly mangled? Worked for 30 years - ought to work for another 30.

[David T]

Well, there you have it! No wonder you were having so much trouble, you were using a vise grip! Not only do they not grip as well as a box wrench, they are short so you do not get enough leverage. BTW the O2 sensors on a D are relatively cheap. They do not have a heater. The ones with a heater can be $80-$100 each and most newer cars have 4. It is rare to have to replace all 4 but it can happen. Doing this "cold" is not only very hard, you take a big chance of ripping out the threads besides losing all of the skin off of your knuckles! Some people just have to do it the hard way. Now that you got it out, at least use some Never-Seize so it might come out a little easier someday. Be careful to only put it on the threads, NOT the probe end. Remember to check the intake and exhaust valve clearances (and adjust if necessary) and reset the Lambda counter.
David Teitelbaum

[lazabby]

Well, there you have it! No wonder you were having so much trouble, you were using a vise grip! Not only do they not grip as well as a box wrench, they are short so you do not get enough leverage. David Teitelbaum

We were using box wrenches to begin with. I even rented O2 sensor tools from the auto parts store to try. The biggest problem was the lack of room the in the area where the sensor is. It made it difficult to get a wrench in there and it was difficult to get any leverage. Vice grips in the end and body weight of the individual got it loose.

[mluder]

Well, there you have it! No wonder you were having so much trouble, you were using a vise grip! Not only do they not grip as well as a box wrench, they are short so you do not get enough leverage. BTW the O2 sensors on a D are relatively cheap. They do not have a heater. The ones with a heater can be $80-$100 each and most newer cars have 4. It is rare to have to replace all 4 but it can happen. Doing this "cold" is not only very hard, you take a big chance of ripping out the threads besides losing all of the skin off of your knuckles! Some people just have to do it the hard way. Now that you got it out, at least use some Never-Seize so it might come out a little easier someday. Be careful to only put it on the threads, NOT the probe end. Remember to check the intake and exhaust valve clearances (and adjust if necessary) and reset the Lambda counter.
David Teitelbaum

Are there instructions in the workshop manual for adjusting the intake and exhaust valves? What's the risk if you don't do this?

Steve

[Mike C.]

Crazy question... anyone just use an O2 sensor socket?

[David T]

Yes, there are instructions in the Workshop Manual on how to adjust the valves. This is a required procedure every 30,000 miles because the PRV-6 has solid lifters (not hydraulic which are self-adjusting). Not doing it can have the following effects:
Higher emissions
Lower power
Lower gas mileage
Overheating
Hard starting
Burnt valves
I find that usually only 1 or 2 valves actually require an adjustment, most will be within tolerance. You should have new valve cover gaskets but a lot of times you can reuse the old ones. You do not have to disconnect the hoses on the A/C compressor, just flip it out of the way.
David Teitelbaum

[Totally 80s]

Crazy question... anyone just use an O2 sensor socket?

I went out and just bought the appropriate size socket for it. It's like 23 or 27mm or something. I didn't know their were O2 sensor sockets. How do they differ from a regular socket?

[mluder]

Thanks, David.

I'm replacing my O2 due to a rich running condition... My injectors were bad and I think the O2 got fouled from the high hydrocarbons.

That being said, my car only has 10,000 miles on it - so do I need to adjust valves just because the O2 sensor is being replaced or is there an assumption that the O2 sensor is replaced at 30,000 miles and corresponds to scheduled valve adjustment?

Thanks.
Steve


Yes, there are instructions in the Workshop Manual on how to adjust the valves. This is a required procedure every 30,000 miles because the PRV-6 has solid lifters (not hydraulic which are self-adjusting). Not doing it can have the following effects:
Higher emissions
Lower power
Lower gas mileage
Overheating
Hard starting
Burnt valves
I find that usually only 1 or 2 valves actually require an adjustment, most will be within tolerance. You should have new valve cover gaskets but a lot of times you can reuse the old ones. You do not have to disconnect the hoses on the A/C compressor, just flip it out of the way.
David Teitelbaum

[dmc6960]

I went out and just bought the appropriate size socket for it. It's like 23 or 27mm or something. I didn't know their were O2 sensor sockets. How do they differ from a regular socket?

They are slotted to allow the sensor wire(s) to pass through. Typically made of a more hardened steel as well.

[lazabby]

Crazy question... anyone just use an O2 sensor socket?

Yes. See post 19.

[David T]

With only 10,000 miles I would not think you should have to adjust valves but after 30 years it certainly can't hurt. If you want to skip it I would just reduce the next cycle from 30,000 to 20,000, meaning do not reset the Lambda counter and do a major service when you hit 30,000 miles.
David Teitelbaum

[David T]

The sensor socket is so you do not have to cut off the wire and you can reuse the sensor. If you are replacing it then it doesn't matter. They are also great for use in a confined area where you can't get a socket in, you use a breaker bar on the socket. Even with the socket it helps a lot to use heat.
David Teitelbaum

[DMC5180]

I Bought an O2 sensor socket to remove the the O2 sensor form my old Audi Coupe The socket has a much heaver wall because of the notch in the side. It still flexed/spread open with my 24" breaker bar on it. I gave up on the socket cut the wire off and used a standard deep well. That did the trick. The only good thing about that job was the location of the O2 sensor. It was a straight shot from above. I don't recall if had a torch to heat things before hand. I do have a MAPP gas torch for occasional use wish I had an OXY/ACET set. A rusty car mechanics best tool:biggrin:

Needless to say cutting the wire for a standard 6 point deep socket means your committed to getting it out.

[mluder]

Got the O2 sensor replaced. It was surprisingly easy and took nothing more than an open end wrench.

Good thing I did it too... the old one was black with soot.

Thanks for all the advice.

[DMCMW Dave]

One bit of confusion - and why some people find this job relatively easy, and some are complaining about access - there were two different locations used for the O2 sensor. On right at the "y" in the pipe and one closer to the cat. The one closer to the cat has less room to swing a wrench.

I don't recall offhand but I believe the one closer to the cat is the "later" design. If you have the later one you can see a flat space on the crossover pipe where the old location would have been.

[lazabby]

One bit of confusion - and why some people find this job relatively easy, and some are complaining about access - there were two different locations used for the O2 sensor. On right at the "y" in the pipe and one closer to the cat. The one closer to the cat has less room to swing a wrench.

I don't recall offhand but I believe the one closer to the cat is the "later" design. If you have the later one you can see a flat space on the crossover pipe where the old location would have been.

Ahhh, that makes sense. I have an '83, thus the later style. The access to the plug was very limited and very difficult to get off. A couple of others said they had no problem but they had earlier model cars.