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O2 sensor won't budge.

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bimmerjeeper

NAXJA Forum User
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USA
Kastein did warn me. But, my MPG is 8, so I need to do something. I used the crowsfoot O2 sensor socket from Autozone and a 3/8" ratchet handle. I could not get a long cheater bar around my socket handle since the pavement got in the way. When I pulled, I did see that the entire exhaust was moving. I soaked in some PB, and walked away, but doubt this will work. It sounds like I need to go buy my first MAPP torch and step up into the big leagues. Is MAPP vastly preferable to a propane torch? Does this have a high odds of loosening it? If not, I will just pay a mechanic to do this level of "heavy duty" work.

In other news, I was able to replace my rear liftgate struts. This went smoothly, and is a project that is ideal for accountant types with a basic socket set. No torches, welders, or grinders needed!


Also what does this mean? Feed it wax?
"you're doing it wrong. I've never had one tear out the bung. You got to get the exhaust good and hot, then hit the bung with a torch. Keep the bung hot and feed it wax at the threads. It will pop right out, trust me. I've never used anything more than a box wrench to take out o2 sensors. Burning myself is the greatest risk."



I would leave the O2 sensor alone unless it gives you issues or your fuel economy drops below 15mpg without you driving it like you stole it.

O2 sensors in these things can be a real bastard, especially in the northeast, they like to rust in place. Last time I did one I ended up replacing the downpipe, the studs in the exhaust manifold, and welding, since it tore all the threads out of the bung it threads into. It was pretty annoying because the studs in the manifold were so badly rusted I had to cut them instead of unscrewing the nuts, which resulted in me having to drive them out with a punch and tack weld in some small bolts to replace them.

Basically what I'm saying is... if that sensor doesn't come out easy (and it probably won't, unless it has already been replaced and doesn't need to be done) you want no part of screwing with it unless you're comfortable using 4 pound hammers in tight spaces to drive studs out of exhaust manifolds and/or welding new bungs into exhaust systems. Since the connector is larger than the hex-shaped faces on the sensor, you can't even get a fullsize socket on that will handle full torque, so you'll end up either cutting the connector off to get a real socket on (and thereby committing yourself to getting it done before driving it) or use an o2 sensor socket, a lot of heat, and/or an open end wrench, and possibly rounding it off.

People in rust free areas of the country have it easy.

The two or three I've had seize up on me... I did right after driving and had a propane torch on it. And it put purple marks on the palms of my apparently blue collar freakishly strong hands at the other end of a two foot box wrench chain. It got to the point that I was afraid it was going to tear the bung out of the exhaust pipe because the metal was flexing right around the welds.
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MAPP burns hotter than propane, if your gonna buy a torch and small bottle of gas anyway, might as well get MAPP. I like the torches that have a built in igniter, but i dont think home depot even carries the older style ones without this feature.

When they say feed it wax, they mean heat it up, and touch a candle or chunk of wax to the threads, it'll wick into the threads. Ive never tried this myself, as i live in beautifull southern california.
 
What threads? The threads aren't exposed, b/c the sensor is screwed all the way in. Is it supposed to seep in capillary style like PB blaster supposedly does?
 
Bimmer, if I were you, I would not go near it with a torch. You are just inches away from the fuel rail in that area, directly above!!!! Not a good place to learn your first steps with a flame IMHO!!!

While I do not live in the salt and snow rust belt, I have never once had to use a torch on a rusted joint. I have always succeeded with pen lube nut release agent products like PB blaster, but it has some times taken 3-4 soakings and many hours, like over night, to get it ready to give up. In a shop like a muffler shop time is an issue, so the pros won't waste time waiting around, they go after it with their main tool, a torch.

I do keep 5 brands of pen lube on hand and sometimes use a mix of them to speed it up. I once did a snake oil demo 40 years ago, where a block that had been in standing water had massive rust on it and the spark plug seized with rust that would not come out with a wrench. We soaked it in a PB blaster like product for 30 minutes, and the spark plug came loose with my hand only!!! It had dissolved the rust holding the spark plug on!!! It was so rusty, once the rust dissolved the plug was loose.

If it gets to torch time, take it to a muffler shop (they are dirt cheap), but give the PB Blaster time and multiple coats and try again first.
 
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As you live in a rust area I don't know if this will work, but I have always had good luck with stubborn O2 sensors by running the engine up to operating temperature, then shutting it down and keep trying to work the O2 sensor loose as the engine cools--I think it is the difference in cooling rates that helps get it loose.
 
Hm, when I did mine, I believe I did heat it up. I don't know what Ecomike means about the rail being directly above. The flame would have to go past the exhaust and intake manifold to reach the fuel rail. Just work in a well ventilated area, make sure you don't have fuel leaks and torch away. Here's a good tip, get rid of that shitty O2 sensor socket. In my experience, they just round the sensor itself. Cut the wires at the sensor, since you're replacing it anyway, then get a deep socket 6 point and use that to loosen it. When I got mine out, the threads in the bung were chewed up so if I were you I would keep a thread chaser and some oil ready. You should chase them anyway just for good measure. I believe I picked mine up at Autozone as well.
 
when i lived back east and had a hard time, i just busted off the sensor pretty much down to the hex, then used a regular socket. worked every time.
 
joe_peters said:
As you live in a rust area I don't know if this will work, but I have always had good luck with stubborn O2 sensors by running the engine up to operating temperature, then shutting it down and keep trying to work the O2 sensor loose as the engine cools--I think it is the difference in cooling rates that helps get it loose.
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Doing that after PB Blaster soaking for a good while sounds like a great idea!
 
crimsondragon said:
Hm, when I did mine, I believe I did heat it up. I don't know what Ecomike means about the rail being directly above. The flame would have to go past the exhaust and intake manifold to reach the fuel rail. Just work in a well ventilated area, make sure you don't have fuel leaks and torch away. Here's a good tip, get rid of that shitty O2 sensor socket. In my experience, they just round the sensor itself. Cut the wires at the sensor, since you're replacing it anyway, then get a deep socket 6 point and use that to loosen it. When I got mine out, the threads in the bung were chewed up so if I were you I would keep a thread chaser and some oil ready. You should chase them anyway just for good measure. I believe I picked mine up at Autozone as well.
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You hit the nail on the head fuel leaks, a newbie with a torch for the first time getting into a congested area with PVC wires nearby and fuel only about 6-9" away, and ZERO experience with a flame tool, is a formula for disaster in my book. Better to get a friend that knows how to use a torch to teach him hands on the first time.

I agree that crows foot is best used for installing the new one, and just cut the connector off the old one and get a good grip with a deep socket or I prefer a closed end box wrench. Once it gets loose, with PB blaster it may turn by hand. The last three I changed turned by hand once they broke loose.
 
Vanimal said:
when i lived back east and had a hard time, i just busted off the sensor pretty much down to the hex, then used a regular socket. worked every time.
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LOL, that makes too much sense!!!! :D Good idea!!!
 
Ecomike said:
LOL, that makes too much sense!!!! :D Good idea!!!
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The problem I see with that technique is that if you STILL can't get it out, you have no O2 sensor at all.
 
joe_peters said:
The problem I see with that technique is that if you STILL can't get it out, you have no O2 sensor at all.
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there are always ways. WORST case scenario, cut the bung off and weld on a new one. Or replace the down pipe for relatively cheap. definitely cheaper than getting piss poor gas mileage for a period of time.
 
joe_peters said:
The problem I see with that technique is that if you STILL can't get it out, you have no O2 sensor at all.
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Rule #1, Do no harm. No way I am smashing the existing O2 and then having 90% odds of towing a dead XJ to the mechanic. $40 DIY turns into a $500 repair.

Thanks for the advice. No way I am doing the torch without a lift. Way out of my experience level. And sounds dangerous to have a MAPP torch 5 inches from my pretty face.

I must say, this is yet more evidence of an XJ really being a mechanic's / pro-hobbyist car. Not really a car for regular folk to work on. My friend changed his Hyundai O2 sensor in the AutoZone parking lot in 5 mins. I think he was wearing a suit and tie while he did it. For an XJ, it's a week long project that involves potentially killing or maiming yourself. LOL, no thanks. If the PB doesn't do it after week during the cooldown cycle, it's going to a qualified professional where it belongs. party1:
 
bimmerjeeper said:
Rule #1, Do no harm. No way I am smashing the existing O2 and then having 90% odds of towing a dead XJ to the mechanic. $40 DIY turns into a $500 repair.

Thanks for the advice. No way I am doing the torch without a lift. Way out of my experience level. And sounds dangerous to have a MAPP torch 5 inches from my pretty face.

I must say, this is yet more evidence of an XJ really being a mechanic's / pro-hobbyist car. Not really a car for regular folk to work on. My friend changed his Hyundai O2 sensor in the AutoZone parking lot in 5 mins. I think he was wearing a suit and tie while he did it. For an XJ, it's a week long project that involves potentially killing or maiming yourself. LOL, no thanks. If the PB doesn't do it after week during the cooldown cycle, it's going to a qualified professional where it belongs. party1:
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I disagree with your assessment of the XJ. It's not even complicated as today's cars go. But, if you feel a Hyundai should be in your driveway instead, feel free ;) We have helped more beginner mechanics than you know.

Most of us have never heard of a garage lift, let alone own one ;) A jack, and jack stands are what most folks use to get ground clearance to work on Stock height XJs. But, if you use them wrong, they can be dangerous also. Use them right, and you have one of the safest methods of supporting your vehicle around.

Changing a O2 Sensor (or O2 Sensors on the new ones), is like anything else. On a Jeep, they are under the vehicle, where most of them hide out on 6 and 8 cylinder engines. They get water and road crud splashed on them. Sometimes they rust.

I have personally used the cut and socket method on a Ford Explorer I owned. There was no way that puppy was coming out with a crescent - I tried!. So instead of making a big mess, I cut the wires off at the sensor, heated up the bung with a propane torch and put a deep socket on it. It still resisted, but came out.

FYI, the XJ will run with no O2 Sensor. Car manufactures are not stupid. They know that parts fail. They only put all the fancy parts on to meet emissions ;) So when the Jeep can't find the O2 sensor, it will throw a code, and probably run a bit crappy; but it will run.

-Ron
 
stop blaming the XJ and saying its not user friendly. everyone here thinks it's operator error at this point.

99% of your issues seem to be that you live on the east coast and don't understand what years of the godawful weather out there do to a vehicle and its parts.

I recommend you sell the XJ and buy yourself something brand new with a warranty and included maintenance.
 
bimmerjeeper said:
I must say, this is yet more evidence of an XJ really being a mechanic's / pro-hobbyist car. Not really a car for regular folk to work on. My friend changed his Hyundai O2 sensor in the AutoZone parking lot in 5 mins. I think he was wearing a suit and tie while he did it. For an XJ, it's a week long project that involves potentially killing or maiming yourself. LOL, no thanks. If the PB doesn't do it after week during the cooldown cycle, it's going to a qualified professional where it belongs. party1:
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Your Joking ?
Just Cut the wires, Spray with PB blaster, get a socket/breaker bar on it & it will come out.
PS: Doing it with the engine hot seems to help.
 
You can disconnect the O2 sensor and still drive it. It will run in what is called open loop mode, runs rich, uses more fuel, and will probably light up the CEL check engine light with a code, but it is drivable and PCM needs to be reset anyway, usually after replacing the O2 sensor, or any sensor.

It is not good to drive it for a real long time (like weeks or months) with out a working O2 sensor as it will eventual burn out the catalytic converter, and it uses more gas (wasteful and costly).

The XJ O2 sensor is not any harder to remove if it is not rusted in place than many other vehicles. If it is rusted in place, I don't care what brand vehicle it is, it ain't come off in 5 minutes!!!! :laugh3: Unless you cut it and the bung off with a torch, LOL.

Some vehicles have parts in easy to reach places and others don't. And while one part in one a vehicle may be easy to reach, the next part on the same rig can be a nightmare on any vehicle, even a BMW. Be glad your jeep is not a 2001 California, it has 4 O2 sensors, LOL!

Anyway, it sounds to me like you have made the right choice on this for you. Good luck.


bimmerjeeper said:
Rule #1, Do no harm. No way I am smashing the existing O2 and then having 90% odds of towing a dead XJ to the mechanic. $40 DIY turns into a $500 repair.

Thanks for the advice. No way I am doing the torch without a lift. Way out of my experience level. And sounds dangerous to have a MAPP torch 5 inches from my pretty face.

I must say, this is yet more evidence of an XJ really being a mechanic's / pro-hobbyist car. Not really a car for regular folk to work on. My friend changed his Hyundai O2 sensor in the AutoZone parking lot in 5 mins. I think he was wearing a suit and tie while he did it. For an XJ, it's a week long project that involves potentially killing or maiming yourself. LOL, no thanks. If the PB doesn't do it after week during the cooldown cycle, it's going to a qualified professional where it belongs. party1:
Click to expand...
 
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