The Official Jeep Wrangler TJ Oxygen (O2) Sensor Thread

Excellent thread. Just orders new "correct" sensors. Looking forward to posting my success.
 
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Having spent 3 years working with Superchips after retiring from The Big Blue Oval, I realized that O2 sensors are a maintenance replacement item and should be replaced every 30-35 thousand miles. Trust me when I tell you this.
 
Chris said:
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.
Click to expand...
I was getting ready to purchase the upstream for my 98 2.5 that I just acquired. It has a Japser sticker so I assume not the original engine. The above list has a 98 specific sensor. How would I tell what year engine I have? Any insight is appropriated.
 
Rico Suave said:
I was getting ready to purchase the upstream for my 98 2.5 that I just acquired. It has a Japser sticker so I assume not the original engine. The above list has a 98 specific sensor. How would I tell what year engine I have? Any insight is appropriated.
Click to expand...
Not sure how you can tell the year just from the engine. You may need to post a new thread as I know nothing about the 4 cylinders.
 
@Chris this thread is invaluable! Along the same lines, has anyone had an issue with a CEL (p0421) coming on after changing plugs? I just put in a fresh batch of Autolite XP Iridiums after a CEL and a limp home (P0300). The rig drove like a charm for about 2 days, then threw me the code again.
 
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Pullski said:
@Chris this thread is invaluable! Along the same lines, has anyone had an issue with a CEL (p0421) coming on after changing plugs? I just put in a fresh batch of Autolite XP Iridiums after a CEL and a limp home (P0300). The rig drove like a charm for about 2 days, then threw me the code again.
Click to expand...
I'd start by clearing it and then seeing if it comes back. Could always be a fluke.
 
Chris said:
I'd start by clearing it and then seeing if it comes back. Could always be a fluke.
Click to expand...
I didn’t even think about that...I’ve got 92k on the rig now and I’m leaning towards bad sensors (I already ordered some) but I’ll clear it and see how it goes!
 
So My CEL came on and the codes were for both upstream o2,s, I cleared the code while waiting for new o2,s to get to OZ from Rock Auto but the CEL has not come back and its not using excessive gas. Do they actually need changing or does this just happen sometimes?
Cheers
 
Fishtaco said:
So My CEL came on and the codes were for both upstream o2,s, I cleared the code while waiting for new o2,s to get to OZ from Rock Auto but the CEL has not come back and its not using excessive gas. Do they actually need changing or does this just happen sometimes?
Cheers
Click to expand...
The sensors definitely do go bad and to be replaced...it’s definitely not a frequent thing.
 
Fishtaco said:
So My CEL came on and the codes were for both upstream o2,s, I cleared the code while waiting for new o2,s to get to OZ from Rock Auto but the CEL has not come back and its not using excessive gas. Do they actually need changing or does this just happen sometimes?
Cheers
Click to expand...
And it’s also best to replace the sensors in pairs (according to RockAuto/OEM). Plus they are kind of annoying to replace so you might as well kill 2 birds with one stone. I prefer using an O2 sensor socket as well.
 
Chris said:
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.
Click to expand...
Not sure this was posted, I have an early 2000 TJ I purchased in December 1999, contrary to this chart, some early 2000 6-cylinders may only have 2 sensors, upstream/downstream of the catalytic converter.
 
PJOJeep said:
Not sure this was posted, I have an early 2000 TJ I purchased in December 1999, contrary to this chart, some early 2000 6-cylinders may only have 2 sensors, upstream/downstream of the catalytic converter.
Click to expand...

Yep, 2000 was a split year. Early 2000s had 2 sensors (just like 1999) and later models had 4.
 
Pullski said:
And it’s also best to replace the sensors in pairs (according to RockAuto/OEM). Plus they are kind of annoying to replace so you might as well kill 2 birds with one stone. I prefer using an O2 sensor socket as well.
Click to expand...
Well I dont just want to replace them if I don't need to, I bought all 4 NTKs for my 06 from RockAuto almost 3 months ago after I got the CEL and codes for both upstream only to be told they are no good for my export model by a USA 4x4 specialist in Australia! now given the correct NTKs cost up to $800 in Australia I dont want to change them if I really dont need to. I got all 4 shipped from RockAuto to AU for $180 US including the removal socket.
So my real question is if o2,s cost you as much as they will cost me would you guys still change them if the codes and CEL have not come back in almost 3 months? :)
 
Fishtaco said:
Well I dont just want to replace them if I don't need to, I bought all 4 NTKs for my 06 from RockAuto almost 3 months ago after I got the CEL and codes for both upstream only to be told they are no good for my export model by a USA 4x4 specialist in Australia! now given the correct NTKs cost up to $800 in Australia I dont want to change them if I really dont need to. I got all 4 shipped from RockAuto to AU for $180 US including the removal socket.
So my real question is if o2,s cost you as much as they will cost me would you guys still change them if the codes and CEL have not come back in almost 3 months? :)
Click to expand...
Hahaha I would DEFINITELY hold off on that then! Damn that’s a bummer from down under...
 
I contacted RockAuto and they said the 4 NTK,s I purchased were the same as Mopar which says "USA All 50 states CND plus Export Emissions", my Vin check says Export Emissions so looks like they are good to go. :)
 
Thank you for this thread, it was very helpful. Replaced all four sensors easily using your ngk fitment guide, and in less than 10 minutes. Cleared the check engine light and fault codes. Thanks again!
 
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