The Official Jeep Wrangler TJ Oxygen (O2) Sensor Thread

[BigDan]

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.


Okay, so why don't other sensors (i.e. Bosch) work on our Jeeps?
Glad you asked! Check out this video for a detailed explanation of why other brands of O2 sensors don't work on our TJs:

So which O2 sensors do I need?
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).

Be aware that NTK O2 sensors are identical to NGK and they share the same part numbers. NTK is more common so it will usually be easier to find. Use the same part numbers for NTK as shown below.

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 1, Sensor 2 (Downstream)​

2000 Federal Emissions (Non-Export)​

NGK #23122 - Bank 1 Sensor 1 (Upstream)​

NGK #23099 - Bank 1 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)​

Important Note About 1997-2000 NGK / NTK O2 Sensors
Per this post here, it appears as if NGK / NTK dropped the numbers for the 1997-2000 model year Jeeps with the 4.0 and 2.5 engines. They said that they are going through a "redesign" and that there "should be" new numbers for those years "sometime" in the near future.


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.

Lastly, if you notice your O2 sensor harnesses are not long enough with the new O2 sensors, these O2 sensor extensions will solve the problem.

Thanks Chris , This sticky , So usefull to me !

 

[Suva39]

New to jeeps and TJs, I have a 1997 TJ, 4 cyl 5 speed, code reader shows po138 and 141. Go to check the downstream o2 sensor. Not there! only a hanging electrical plug over the transfer case. Also a metal plug in the catalytic converter. Is this a PO previous owner thing or did any TJs come with one O2 sensor?
Thanks suva39

 

[reddvltj]

New to jeeps and TJs, I have a 1997 TJ, 4 cyl 5 speed, code reader shows po138 and 141. Go to check the downstream o2 sensor. Not there! only a hanging electrical plug over the transfer case. Also a metal plug in the catalytic converter. Is this a PO previous owner thing or did any TJs come with one O2 sensor?
Thanks suva39

Previous owner, definitely!!

Both itterations of the '97 (early and late) had 2 sensors, pre and post cat. You want to make sure you pay close attention to the production date when looking for parts and sensors.

 

[Austin O.]

I’m assuming since this hasn’t been updated, the ntk 97-00 o2 sensors aren’t available yet. I’m getting bad gas mileage, replaced spark plugs, didn’t make a difference. Do I just need to wait until ntk o2 sensors for a 98 tj are available to try to see if that’s the problem? Any other options? Thanks!

 

[reddvltj]

I’m assuming since this hasn’t been updated, the ntk 97-00 o2 sensors aren’t available yet. I’m getting bad gas mileage, replaced spark plugs, didn’t make a difference. Do I just need to wait until ntk o2 sensors for a 98 tj are available to try to see if that’s the problem? Any other options? Thanks!

The best thing to do would be to call NTK/NGK directly.

I haven't followed up with them since I talked to them in mid October.

 

[Bearcat]

My 05 rubicon LJ 4.0 O2 sensor harness plugs don’t match up w the new NTK 23018 and 23160 upstream sensors ????

 

[reddvltj]

My 05 rubicon LJ 4.0 O2 sensor harness plugs don’t match up w the new NTK 23018 and 23160 upstream sensors ????

Two things come to mind as to why they don't fit.
1. A previous owner spliced in different harness side plugs to fit incorrect sensors
2. The sensors you got are packaged incorrectly.

The NGK/NTK site isn't showing O2 sensor information any more for TJs unfortunately.
RockAuto is showing those same numbers for the Bank 1 and 2 Upstream sensors and the information in the first post was accurate as of the last time I spoke with a tech at NTK, which was back in October.

It's looking more like they dropped them all together after seeing their site today.

 

[fnx14]

Two things come to mind as to why they don't fit.
1. A previous owner spliced in different harness side plugs to fit incorrect sensors
2. The sensors you got are packaged incorrectly.

The NGK/NTK site isn't showing O2 sensor information any more for TJs unfortunately.
RockAuto is showing those same numbers for the Bank 1 and 2 Upstream sensors and the information in the first post was accurate as of the last time I spoke with a tech at NTK, which was back in October.

It's looking more like they dropped them all together after seeing their site today.

Hey guys, new here but usually lurk and find my answers.

Anyways, I talked to NTK today (Actually Monarch Products) and they basically said these sensors have not been dropped and they also wouldn't say that they are developing new ones.

I called Napa today and he checked nationwide inventory and there are a bunch scattered across the country. I ordered online and it should be here in 2 days. If it actually arrives I will report back that this might be a source for now.

 

[Link]

Maybe I should pick up some spares. The NTK ones are listed on RockAuto and show to be in stock. I bought a couple of them a month and a half ago and they worked great.

 

[reddvltj]

Hey guys, new here but usually lurk and find my answers.

Anyways, I talked to NTK today (Actually Monarch Products) and they basically said these sensors have not been dropped and they also wouldn't say that they are developing new ones.

I called Napa today and he checked nationwide inventory and there are a bunch scattered across the country. I ordered online and it should be here in 2 days. If it actually arrives I will report back that this might be a source for now.

NTK/NGK isn't owned by Monarch... Monarch sells NGK products.

I spoke directly with NTK back in October and here's the link to what they told me then. At the time you could still look up the application data for O2 sensors for TJs. Since then they nolonger support the O2 sensor look up...

https://wranglertjforum.com/threads...-tj-oxygen-o2-sensor-thread.4068/post-1210205



As far as finding a source for future purchases, my guess is when all the supply houses sell out that'll be it... unless NTK starts producing them again.