The Official Jeep Wrangler TJ Oxygen (O2) Sensor Thread

Thanks. So glad to be a part of this great group. I will soon be ordering all 4 sensors for my ride. Now if I can just get my tranny figured out I’ll be ecstatic
 
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Let us know how it works out! ;)
I sprayed the O2 sensors down with PB blaster a few times over a few days. They came out with no effort, and I mean no effort. I tightened up the exhaust bolts why I was under there. Had a little bit of wiggle. Solid now. My issue seems to be better, but not fixed. Jeep doesn’t like mild hills or freeway speed at the moment. Might have the cats tested next, and do a compression test. I’ve already been thru the throttle body, did a fuel pump test, checked the plugs and put a new coil pack on. Frustrating. No codes at the moment. I’m gonna look thru the forum now for any similar issues.
 
I sprayed the O2 sensors down with PB blaster a few times over a few days. They came out with no effort, and I mean no effort. I tightened up the exhaust bolts why I was under there. Had a little bit of wiggle. Solid now. My issue seems to be better, but not fixed. Jeep doesn’t like mild hills or freeway speed at the moment. Might have the cats tested next, and do a compression test. I’ve already been thru the throttle body, did a fuel pump test, checked the plugs and put a new coil pack on. Frustrating. No codes at the moment. I’m gonna look thru the forum now for any similar issues.

I would do a compression test, but my money is now on clogged cats. The symptoms you have sure sound like what happened with mine when the cats were clogged. Sometimes they don't throw any codes too until they are about ready to fully give out.
 
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Got my new relay, and installed it. She hasn't thrown a code since. Wanted to wait and drive it a bit to make sure but looks like that fixed it! Thanks to the guy who suggested it.
Now just have to figure out the death wobble. That's a whole other string.
 
Got my new relay, and installed it. She hasn't thrown a code since. Wanted to wait and drive it a bit to make sure but looks like that fixed it! Thanks to the guy who suggested it.
Now just have to figure out the death wobble. That's a whole other string.

Awesome, thanks for the update! A relay is something I wouldn't have thought of.
 
Got my new relay, and installed it. She hasn't thrown a code since. Wanted to wait and drive it a bit to make sure but looks like that fixed it! Thanks to the guy who suggested it.
Now just have to figure out the death wobble. That's a whole other string.
Thanks for updating this. I am getting ready to change all of my o2 sensors on my 2004 as preventative maintenance...chasing down a rough idle and slow start condition (replaced other applicable sensors and cleaned/changed IAC and throttle body as well as plugs to no avail)... Not throwing any codes at present. Engine seems to have good power, no hesitation, getting 11-13mpg in town. Thinking I should buy a relay too since they are cheap.

My TJ has 52k on it. Wondering if I should change the pre-cats while I am down there. The flowmaster with the pre-cats and 3rd cat is only $250. Which is way cheaper than the Eastern one... Unless I am missing something.

Oh and @Chris - Thanks so much for this and all the other informative threads. So many of us would be lost without everything you've done...
 
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My 04 Jeep LJ with 170,000 miles died (but came back to life) and is showing code which consensus on this thread seems to be try sensors first and pre-cats if that doesn't work. I've been under it and seems easy enough to change the sensor itself but the wiring plug looks like it is on the backside of the engine which is not easily accessed - any tips on getting to it?
 
My 04 Jeep LJ with 170,000 miles died (but came back to life) and is showing code which consensus on this thread seems to be try sensors first and pre-cats if that doesn't work. I've been under it and seems easy enough to change the sensor itself but the wiring plug looks like it is on the backside of the engine which is not easily accessed - any tips on getting to it?
Steep stool made it easier. I had to pull the wire harness a little out of the way to get my hand in there. Wasn’t too bad tho.
 
Hello everyone. I have been reading this forum for a long time. Thanks for all the posts. It's help me so many times. This is my first post. I have been chasing a P0431 and now P0421 code for about a year. I have replaced O2 sensors with NTK sensors (All 4) and new pacesetter cat set because of an original cat blown out and and code. Still have codes after replacing cats. I am also getting 8 mpg. A side note: The flanges seem to loosen from time to time and I tighten them (code still comes back after tightening even though it sounds better or more "sealed"). The factory bolt and clip/nut combos don't seem to do the trick. Even with brand new ones. I have also added an extra mounting point from the passenger side of the engine for the exhaust piping. Finally gave up and took it to the stealership (only because I was going for the the clutch switch recall) and they said I need all new Mopar O2 sensors and factory cats ($2500). Um... I don't think so. They said that NTK won't work. Is there some truth to this? I have contacted pacesetter and they are sending me a new cat set under warranty. Yippy! The Y pipe didn't fit right when I first installed it. I think that may have been the problem all along. Pacesetter said it might be a defect and the Y pipes were taken out of the weld mold before it was all the way cooled. Has this happened to anyone else? Has anyone else found a better way to bolt the flange on? There is almost no room to not use the clips from when I see. I tried to get extra (thin) nuts on top but also no room. Thank you so much.
 
So I’ve had a P0161 code for a decent while, and I just want to ask how quickly I should get it repaired. I haven’t noticed drivability issues and the light hasn’t been flashing so I’ve been putting it off.
 
So I’ve had a P0161 code for a decent while, and I just want to ask how quickly I should get it repaired. I haven’t noticed drivability issues and the light hasn’t been flashing so I’ve been putting it off.

I would get it fixed as soon as funds and time permit.
 
Would you reccomend replacing all?

Yes, replace ALL of the O2 sensors. The stupid thing to do is replace only one of them. O2 sensors are normal wear and tear maintenance items that should all be replaced around 80k miles. Especially if you want your engine to run as good as possible. With as cheap as they are too, there's no real reason not to replace them all.

Not like a BMW where each O2 sensor is around $150 a piece!
 
Hi,
I got a P0141 error to replace sensor Bank 1/sensor 2.
I bought all 4 O2 sensors for my TJ 2001 4.0L Automatic Sahara, right wheel drive (Exported). I double checked with Rockauto and also NGK website to be sure I get the right sensors.
NGK #23139 - Bank 1, Sensor 1 (Upstream)
NGK #23138 - Bank 2, Sensor 1 (Upstream)
NGK #23142 - Bank 1, Sensor 2 (Downstream)
NGK #23141 - Bank 2, Sensor 2 (Downstream)
My mechanic guy searched thoroughly under the vehicle and insisted that there only 2 sensors to replace, one before the catalyst and one after.
What are we missing? where are the other sensors located? the diagram on the first post here doesnt look like what I have in regards to sensor location. am I supposed to use only 2 sensors, like a 4 cylinder engine? many thanks for the help.
Hello
I finally found the second O2 sensors.
I think it's the same thing like you... For my 2002 4.0 sport there are only two O2 sensors not 4... I wanted to knew what did you do...? Did you install new sensors? Does it worked for you...?

Envoyé de mon MHA-L29 en utilisant Tapatalk
 
Hello
I finally found the second O2 sensors.
I think it's the same thing like you... For my 2002 4.0 sport there are only two O2 sensors not 4... I wanted to knew what did you do...? Did you install new sensors? Does it worked for you...?

Envoyé de mon MHA-L29 en utilisant Tapatalk
I would get under the driver side of the vehicle and look. You’ll be able to see both catalytic converters. If you only have one cat then you’ll need to replace two sensors, if you have two cats then you’ll need to replace 4 sensors.
 
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I just replaced all of the O2 sensors on my 2004 4.0, and Rockauto shows NTK 23531 for bank 2 sensor 2 instead of 23131... Did I put the wrong one in or are these interchangeable? I haven't had any issues in the month since I installed it though.

Also, for those here researching O2 sensor codes, mine threw an O2 sensor code, but I'm not sure any were actually bad, because the root of the problem was one of the precats broke up and was clogging the exhaust... But I was at 90k miles and decided to replace all the sensors anyway while I replaced the cats. So make sure there isn't some other problem causing the O2 code. If you're on all original parts and getting up there in miles it might be a good idea to just replace everything anyway - it's easier to access the O2 sensors when the downpipe is out. Total cost for 4 sensors and downpipe with precats and new cat was about $450. I probably could have saved a few $ somewhere else, but Rockauto was able to get everything to me the fastest.
What did you torque the sensors to? I wouldn’t want to break them