The Official Jeep Wrangler TJ Oxygen (O2) Sensor Thread

Whole process took 15minutes. Getting the harness off is the hardest part (little flat head between detent after pressing it down) spreads open easy. Now for the moment of truth, starting it and seeing if the error codes return!!!!
 
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Whole process took 15minutes. Getting the harness off is the hardest part (little flat head between detent after pressing it down) spreads open easy. Now for the moment of truth, starting it and seeing if the error codes return!!!!
Ok replaced both upstream O2's and let it run for about 10 minutes and check engine light is still on. So I'm banking on I need to clear the codes. Any sneaky ways besides disconnecting the battery? I have heard you can run 50 miles and the computer will run a new diagnostic on it but with 35's not looking to burn a 1/4 tank of gas.
 
Other than a code reader those are your options


There must have been a time
when we could have said no.
 
Chris, thank you for this information. I would typically scoff at this type of comment, but I stumbled across this thread after I had replaced all the sensors with Bosch. I was not only getting the same errors as before but new errors. After two weeks of running Bosch, I replace each sensor one at a time with the NGK's. After each sensor replacement, I did a test drive. After each test drive, a few errors dropped off the list. With the NGK's. all the errors are gone. Fortunately, Amazon gave me a refund on the others.

Thank you again. This is great information.
 
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Chris, thank you for this information. I would typically scoff at this type of comment, but I stumbled across this thread after I had replaced all the sensors with Bosch. I was not only getting the same errors as before but new errors. After two weeks of running Bosch, I replace each sensor one at a time with the NGK's. After each sensor replacement, I did a test drive. After each test drive, a few errors dropped off the list. With the NGK's. all the errors are gone. Fortunately, Amazon gave me a refund on the others.

Thank you again. This is great information.

Happy you found it! Most people think we're just being snobs when most of us tell them, "Never use any replacement sensors other than OE Mopar ones." It's the truth though, and it's more than just the O2 sensors as well, it's ALL the sensors! I know people who have used aftermarket brand replacement crankshaft position sensors for instance, and they didn't get rid of the issue or the check engine light.

I don't know what it is, but it seems our TJs really don't like aftermarket sensors. It's odd, because usually that's not the case with other vehicles, just our Jeeps.

I shudder to think of what will happen once Mopar stops making all the sensors for our Jeeps (which they already are for the most part). Then us TJ owners are really going to have to try and figure out a solution.
 
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I have a 1998 TJ with a 2.5L. I ordered the upstream o2 sensor (NGK #23506) from amazon, but it is not the correct part. According to the vendor I need NGK #23151...before I send #23506 back I just wanted to confirm with the community I have the wrong part. Any help will be greatly appreciated. Thanks!
 
I have a 1998 TJ with a 2.5L. I ordered the upstream o2 sensor (NGK #23506) from amazon, but it is not the correct part. According to the vendor I need NGK #23151...before I send #23506 back I just wanted to confirm with the community I have the wrong part. Any help will be greatly appreciated. Thanks!

So odd! I just checked NGKs official parts catalog, and of the 2.5 liter engines, the ONLY year that requires 23151 in the upstream position is the 1998 model. All the other models (1991, 1999, 2000, etc.), require 23506. That's very, very bizarre, but that part number you need is indeed correct. I updated the original post.

What a weird one!
 
So odd! I just checked NGKs official parts catalog, and of the 2.5 liter engines, the ONLY year that requires 23151 in the upstream position is the 1998 model. All the other models (1991, 1999, 2000, etc.), require 23506. That's very, very bizarre, but that part number you need is indeed correct. I updated the original post.

What a weird one!
Thank You, Chris!
 
What are Bank 1, Bank 2, etc.?
Since this question pops up from time-to-time, here's an easy to follow diagram that illustrates what they mean when your OBDII code scanner (or manual) tells you something like "O2 sensor, Bank 1, Sensor 2":

View attachment 12208


What does upstream and downstream mean?
Simple, upstream means the O2 sensor is "upstream" of the catalytic convertors, meaning before the catalytic convertors. Downstream means the O2 sensor is "downstream" of the catalytic convertors, meaning after the catalytic convertors.


What brand of O2 sensors should I use for replacements?
Pay close attention to this one so you can do it once and do it right! The Jeep Wrangler TJ is extremely sensitive to all oxygen sensors other than NGK / NTK. Bosch O2 sensors and all the others (including the crappy Chinese brands you'll buy at your local auto part store) are very well documented as not working properly with our TJs. In other words, you plug them in and you assume all is well, until you notice your check engine light isn't going away. This is almost always due to the fact that you didn't use an NGK / NTK replacement O2 sensor.

I'm going to break down which sensors you need based off what year your TJ is. The part numbers (and information) below were taken directly from the NGK website, so you can assure it is 100% accurate (even double checked each individual year and model before writing this thread).

4 Cylinder Engines

1997-2000

NGK #23506 - Bank 1, Sensor 1 (Upstream)
NGK #23151 - Bank 1, Sensor 1 (Upstream) (1998 ONLY)
NGK #23099 - Bank 1, Sensor 2 (Downstream)

2001-2004
NGK #23138 - Bank 1, Sensor 1 (Upstream)
NGK #23141 - Bank 1, Sensor 2 (Downstream)

2005-2006
NGK #23159 - Bank 1, Sensor 1 (Upstream)
NGK #23159 - Bank 1, Sensor 2 (Downstream)


6 Cylinder Engines

1997-1999
NGK #23151 - Bank 1, Sensor 1 (Upstream)
NGK #23099 - Bank 2, Sensor 2 (Downstream)

2000
NGK #23122 - Bank 1, Sensor 1 (Upstream)
NGK #23506 - Bank 2, Sensor 1 (Upstream)
NGK #23099 - Bank 1, Sensor 2 (Downstream)
NGK #23099 - Bank 2, Sensor 2 (Downstream)

2001-2003
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)

2004
NGK #23137 - Bank 1, Sensor 1 (Upstream)
NGK #23135 - Bank 2, Sensor 1 (Upstream)
NGK #23132 - Bank 1, Sensor 2 (Downstream)
NGK #23531 - Bank 2, Sensor 2 (Downstream)

2005-2006
NGK #23018 - Bank 1, Sensor 1 (Upstream)
NGK #23160 - Bank 2, Sensor 1 (Upstream)
NGK #23159 - Bank 1, Sensor 2 (Downstream)
NGK #23158 - Bank 2, Sensor 2 (Downstream)

Misc Installation Notes
When installing new O2 sensors, be certain to use some anti-seize on the threads of the new O2 sensors! This is important, and will save you a huge headache should you ever need to remove them in the future.

In addition, a O2 sensor socket will greatly aide in the installation and removal of O2 sensors. I recommend this one.

Hey Chris/everyone. My first post and I just replaced all 4 oxygen sensors on my 2000 wrangler 4.0 and the NGK bank1 sensor1 (#23122) was too short. Any suggestion as to the correct sensor #. The NGK website says I can use the downstream sensor #23099 for B1S1. Any suggestion would be appreciated. The info here is amazing.
 
Hey Chris/everyone. My first post and I just replaced all 4 oxygen sensors on my 2000 wrangler 4.0 and the NGK bank1 sensor1 (#23122) was too short. Any suggestion as to the correct sensor #. The NGK website says I can use the downstream sensor #23099 for B1S1. Any suggestion would be appreciated. The info here is amazing.

I'd go with what the NGK website says in that case and use NGK #23099 since their website says you can use that as well. It mentions that being for California emissions, but TJs are 50 state vehicles (meaning they didn't make a California model only like they did with some older vehicles), so you should be fine!
 
I'd go with what the NGK website says in that case and use NGK #23099 since their website says you can use that as well. It mentions that being for California emissions, but TJs are 50 state vehicles (meaning they didn't make a California model only like they did with some older vehicles), so you should be fine!
All hail Chris. Thanks you
 
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installed a new ntk bank 1 sensor 1 - 02 sensor on my 2005. I pulled a Mopar 56028995AB out...was hoping it was an off brand instead. We will see if the codes stop. Chris thanks for the tip on the 02 socket...I figured I could just use an open end wrench on it but that would have been a real PIA...now I have another tool to add to the collection and who does not like that!
 
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Well.....just replaced all 4 02 sensors on my 2000 wrangler. Still throwing codes 135,141,146. I do have 455 evap leak. Would/could this cause the 02 sensors to still fail or is there a bigger issue. I don’t have an obd2 to see real time problems. Thanks, Kirk
 
did you replace them with NTK brand? Sometimes sensors do there job and report an actual problem...although it does seem the answer to most codes is the sensor itself.
 
I have burned up (broken inside shell) 3 Cat converts in the past 5K miles. I have 2000 TJ (55K miles, original owner) with 1 upstream and 1 downstream sensor. No codes thrown, runs/idles fine ... but after a few trail runs the CATCO replacements start to rattle (and break up).

Spent about $1K trying to get to root cause and trusting my rig again. I had it stressed tested on dyno and it leans/trims out fine. Took it to some mechanic's mechanic (w/aftermarket sensor tools) that show nothing is wrong (except that I am missing 2 sensors).

Finally, took it to dealer to confirm old computer software IS working, but they noticed slow response in upstream O2. Still, they said the likely problem is too much air flow from aftermarket cold air intake.

This forum said ... "the dealer statement about CAI allowing too much air is junk".

I am thinking to replace both O2 sensors, but a 2 sensors 2000 TJ is an "odd duck", as stated earlier. Even the NGK site is expecting 4 sensors on this duck.

1.) Can I get a definitive NGK part match??