The Official Jeep Wrangler TJ Oxygen (O2) Sensor Thread

[Chris]

So it triggers the following questions: do these 2 sensors only differ in their connectors? Are all upstream sensors for Jeeps the same and only differ in their connectors? And, if so, why do they change the connectors, creating more part numbers and more mess?

I'm not sure anyone can answer that for you other than NGK themselves, so it would be worth asking them.

Unless of course someone has actually compared both sensors with a multimeter to see how they work and if they are the same.

I also can't tell you if all upstream sensors are the same as I've never compared them. These are tough questions, ones that you may not find the answer to easily without either testing different sensors or asking NGK.

Still, I hope someone responds who may have knowledge of this, I just wouldn't hold my breath.

 

[Leroy_TJ]

Corrected issue with O2 sensor code P0058, the new sensor was bad. Had it tested today and replaced no more codes. Hopefully it will last this time.

 

[Aussie Phil]

Update: After Googling on NTK 23151 and comparing it to the Upstream O2 sensor that i had (Mopar 56041887AA), i found out that the connectors are incompatible (NTK 23151 being a round one). So, i sent a message to NGK requesting their part number for Mopar's 56041887AA. They suggested NTK 23138, which is actually the Upstream sensor of the 2.5L. I ordered it and it looked almost like the Mopar one that i had. The only difference was that the slot on one side of the connector was not lining up correctly (photo included). Then i trimmed the plastic tab that didn't align (i thought that this would be easier than cutting and replacing the connector with the old one). Plugged it in, removed the positive battery pole for about 10 minutes to clear the error codes and voila, no more error codes. Been driving the Jeep for some time now with no problems. Therefore, for an EU spec 2002 TJ Sport with the 4.0L and only 2 O2 sensors, Mopar's 56041887AA has the NTK 23138 (with minor trimming) as an equivalent. So it triggers the following questions: do these 2 sensors only differ in their connectors? Are all upstream sensors for Jeeps the same and only differ in their connectors? And, if so, why do they change the connectors, creating more part numbers and more mess?

Good afternoon everyone from Spain. First of all, I wish you good health to everyone. This is my first post in this forum and I hope not be complicated in my question. I quote three posts that I think are contradictory. Nobody in Spain solves the question about which are the NTK references for a TJ 4.0 from 2001 that only has two oxygen sensors.
Sorry for my poor writing. Thank you so much.

Just what I needed to know. Replacing my o2 due to bad fuel consumption. I have the same part number but noticed they are more expensive. Would like to know how you go with your fuel consumption now with the new sensor.

 

[Nacho]

I've made a mistake.
I quoted three post: one post from Phuket and two post from Jeepnut.
My post with my question starts below.
I have quoted these three posts because they are contradictory and I still don't know which correct ntk references are for two O2 sensors that my 2001 tj 4.0 has only.

 

[Reign Mack]

My right hand drive 2002 4.0 Sahara had the P0138 code.
The black one is from Crown: 56029049AA
White is the NTK: 23142

I ended up putting the crown one in as the tab on the side of the stock one did not match the NTK

I had to take my Jeep down to my mechanic in the end the sensor was rusted and burned on and super tucked away behind the flange pictured, he had to drop the transfer case skid plate and use a torch to heat up the sensor to remove it.

 

[junknstuf]

hey chris, junknstuf here. I see where you recommend NGK sensors, and I see the ngk and ntk have the same part #s are they the same?

 

[Davidhintsa]

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).

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​

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.

Can having o2 senors go bad cause the Jeep to randomly stall while driving?

 

[Chris]

Can having o2 senors go bad cause the Jeep to randomly stall while driving?

A bad upstream O2 sensor can absolutely cause that, as well as plugged catalytic convertors.

 

[jesuspalomino]

Wish I had some photos to demonstrate my problem I've come across but I'll try my best. Recently swapped out my whole exhaust kit by Crown Automotive (only full kit I found online) for my TJ 97' 2.5L. Figured that while my exhaust was already down it would be a good idea to change both my O2 sensors. After ordering my upstream and downstream from NGK, my mechanic I took took it to wasn't able to do the job because the downstream #23099 did not have the same output as my old one. Curious if any 2.5'ers experienced this issue themselves? Was thinking about swapping the old connector on my old O2 sensor and replacing it on my new one. Would this be just as efficient? If that wouldn't work, my last resort would be to get a different brand O2 sensor which is what I don't wanna do as Chris strictly recommends NGK for the TJ family

 

[reddvltj]

Wish I had some photos to demonstrate my problem I've come across but I'll try my best. Recently swapped out my whole exhaust kit by Crown Automotive (only full kit I found online) for my TJ 97' 2.5L. Figured that while my exhaust was already down it would be a good idea to change both my O2 sensors. After ordering my upstream and downstream from NGK, my mechanic I took took it to wasn't able to do the job because the downstream #23099 did not have the same output as my old one. Curious if any 2.5'ers experienced this issue themselves? Was thinking about swapping the old connector on my old O2 sensor and replacing it on my new one. Would this be just as efficient? If that wouldn't work, my last resort would be to get a different brand O2 sensor which is what I don't wanna do as Chris strictly recommends NGK for the TJ family

I can't remember if it makes a difference with the O2 sensors or not but there were 2 different releases for the 97 model year. Early and late. I believe there are a couple differences electronically between the two. Maybe NGK/NTK can help sort it out.

 

[jesuspalomino]

I can't remember if it makes a difference with the O2 sensors or not but there were 2 different releases for the 97 model year. Early and late. I believe there are a couple differences electronically between the two. Maybe NGK/NTK can help sort it out.

Im gonna have to start doing research on that. Do you know if this applies to just manuals or automatics?

 

[reddvltj]

Im gonna have to start doing research on that. Do you know if this applies to just manuals or automatics?

Unfortunately, I do not know the answer to that. I could be completely off about the O2 sensors, that's why I suggested contacting NGK directly. The 2000 model year had some discrepancies that I had to call and talk to them directly to figure out. The tech I spoke to was very helpful.

 

[rlinares40]

I have a 06 Wrangler Sport with a P0038 code that will not go away. i've changed the o2 sensor twice and cleared the code with no luck. something to note is that the voltage for that sensor (B1S2) is always at a constant voltage of 1.27. anyone know why this would happen?

thanks in advance

 

[Kerry]

I got a P2096 code (downstream O2 sensor). It made sense once I discovered the bolts holding the cats on were very loose, so the lower sensors were getting a little to much O2!

Little bit tricky trying to get to the top of the bolts, but 5 min fix once I knew what it was, 2+ hours trying to figure it out, lol.....(but I do have very clean groundstraps now....)

 

[Josh Harder]

I'm replacing all 4 on my 04 lj. I noticed the previous owner had one of the downstream ones replaced about 8000 kms ago. Should I replace that one as well or save the new one for when I will need it down the road?

 

[E. Weaver]

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).

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​

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.

Ok, I just ordered the NGK's for my 2005 TJ. Amazon said the #23159 wouldn't fit - I read a few reviews and ordered it anyway. Fingers crossed.

 

[Chris]

Ok, I just ordered the NGK's for my 2005 TJ. Amazon said the #23159 wouldn't fit - I read a few reviews and ordered it anyway. Fingers crossed.

Unfortunately Amazon isn't right all the time. Most of the time they are, but sometimes they aren't.

 

[E. Weaver]

Unfortunately Amazon isn't right all the time. Most of the time they are, but sometimes they aren't.

Yep - thanks.

 

[zyclotron]

New NGK o2 Sensor plug does not match.

Hey there,

before writing new post, I am gonna try to tag onto this one.

I am restoring my TJ and in the process of replacing the exhaust system, I am replacing all 4 O2 sensors.
I stumbled over Chris post about NGK and went to buy the ones from NGK.
————————-

I have a 2000 Tj (4.0) with calif emission system and it turns out my new Bank1 Sensor1, NGK Sensor has a black PLUG. The receiver however is Grey.... which does make sense because it appears that the pre CAT are suppose to be grey and post CAT black.
I called NGK and they couldn't really contribute to my problem. They persist, the one I got is the one that goes in there. The o2 sensor that was in there before was 56041212 AE, which according to them does not belong in there. Doing a lot research on this I realize the color is sometimes black, sometimes grey. Crayz... As posted earlier on this thread....crown even provides one plug that covers all options.

Does it matter? are the upstream sensors all the same?

At this point I am planning to replace the plug from my new NGK sensor to a grey one... although I have not been able to 100% confirm if that will work.

any ideas ?


much appreciated.

 

[LJMolina]

So, I bought my 2006 LJ back in Jan this year... it was running great and was getting about 190-200 miles to the tank (~12 mpg)... two weeks ago I got a P code to replace my B1S1 O2 sensor... since this jeep has 118k miles on it I thought to replace all O2 sensors while I am it since I dont know the last time the previous owner replaced them. I followed this forum about replacing the Bosch sensors with NGK... Now, I'm getting at best about 150-160 Miles to the tank (~9 mpg). Nothing else changed, I'm not getting the engine light... but one thing I did notice is the response to acceleration is sluggish...Running Rich?

I dont know what to do or check.. please help.