The Official Jeep Wrangler TJ Oxygen (O2) Sensor Thread

Hello It's Me Again said:
Any info is appreciated!! I keep getting the upstream and downstream codes on my 97 TJ 4.0 6 cyl. I bought the Bosch sensors and another brand (not sure what) and the connectors on the new ones are female but the ones in my Jeep at the moment are male. I cannot find any that are male online. What in the world is happening?? I replaced them about 2 years ago, didn't think I'd have to do again so soon but now I'm left scratching my head because none of the available ones have the correct connector!! Do I have to buy new parts that go from the engine to the sensor connection? Seriously confused at this point!! Any help, info, tidbits would be appreciated!!
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Chris said:
Shouldn’t have bought Bosch. If you read the first post in this thread it specifically mentions only using NGK / NTK sensors. Bosch sensors are known to cause issues.
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To add to this you also need to make sure you are getting the correct sensors for the production date of your '97.
 
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Brucey69 said:
Hey guys,

New to the forum with a brain buster for anyone who might be able to help.

I have an 01 TJ 4.0 in Australia that I bought at the end of last year, I’m the 3rd owner and it’s my first ever Jeep, 192,000kms. Not a whole lot of issues so far, but a couple of weeks after I bought it, I had a CEL for crank/camshaft sensor, so I replaced both the crankshaft sensor and the camshaft sensor/synchronizer and the light went away. Happy days.

I recently got a CEL for the P0133 code (I believe it is the bank 1/sensor 1 code for slow response??) - doing the on/off ignition trick.

I have been getting terrible mileage since I bought it (but I also don’t really know what good is being my first Jeep), and thought that after replacing the crank/camshaft sensors it would get better. After reading that you get poor mileage due to bad o2 sensors, I decided after looking at this thread, I may as well replace all the o2 sensors for good measure. Got all 4 sensors according to the part numbers posted on here so should be all good.

Now the fun part…

Looking at the diagram for the 4.0L engine, I should have 4 sensors, and two cats right up against the manifold right? Wrong. No cats up near the manifold, looks like I’ve only got one under the skid plate, and only 2 sensors, one before the cat, and one after the cat. Refer to pictures. 1st pic is before cat, 2nd pic is the exhaust going into the manifold and actually looks like there are bolts in where the sensors should be and the 3rd pic is the cat/sensor after cat.

So I’m assuming the owners before me potentially modded this?! After looking at the VIN, double checking I’ve got 6 spark plugs (lol), and checking everything telling me this is a 4.0 6 cylinder engine, I’m not crazy am I?! Any idea on what sensors the two I have would be? TIA!

View attachment 322595

View attachment 322596

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My exhaust is identical to yours. Two "screw plugs" in exact same spots. Same as o2 sensors. My jeep is a year 2000. Did you ever figure out more info about this? Heres a video of my exhaust.
 

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Sensei said:
My exhaust is identical to yours. Two "screw plugs" in exact same spots. Same as o2 sensors. My jeep is a year 2000. Did you ever figure out more info about this? Heres a video of my exhaust.
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Your TJ's exhaust may "look" like the person's jeep that you quoted but unless you brought an "export" TJ back into the US it is not the same sensors he needs.. 2000 model year had 2 different non-export configurations. California emissions, has the 4 sensor config. Federal emissions, has the 2 sensor config.

Here are the 2 you need for 2000 (NON-export) federal emissions.

https://www.amazon.com/gp/product/B001PN8UD0/?tag=wranglerorg-20

https://www.amazon.com/gp/product/B001PNCKJA/?tag=wranglerorg-20
 
reddvltj said:
Your TJ's exhaust may "look" like the person's jeep that you quoted but unless you brought an "export" TJ back into the US it is not the same sensors he needs.. 2000 model year had 2 different non-export configurations. California emissions, has the 4 sensor config. Federal emissions, has the 2 sensor config.

Here are the 2 you need for 2000 (NON-export) federal emissions.

https://www.amazon.com/gp/product/B001PN8UD0/?tag=wranglerorg-20

https://www.amazon.com/gp/product/B001PNCKJA/?tag=wranglerorg-20
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Where would I find the second o2 sensor? I only see the one upstream of the cat next to my trans, inside the skid plate.
 
reddvltj said:
Hey @Chris could you maybe edit the first post to add the Federal Emissions model to the 2000 Model year and maybe put a not that Export is not the same even though it looks the same.


2000 Federal Emissions (Non-export)
NTK #23122 - Bank 1 Sensor 1 (Upstream)
NTK #23099 - Bank 1 Sensor 2 (Downstream)
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Thanks, I’ll do this.
 
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Sensei said:
Where would I find the second o2 sensor? I only see the one upstream of the cat next to my trans, inside the skid plate.
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The first ne is right before the cat and the second one is right after it between the cat and the muffler pointed up at a slight angle towards the body tub.

1661741443679.png
 
reddvltj said:
Hey @Chris could you maybe edit the first post to add the Federal Emissions model to the 2000 Model year and maybe put a note that Export is not the same even though it looks the same.


2000 Federal Emissions (Non-export)
NTK #23122 - Bank 1 Sensor 1 (Upstream)
NTK #23099 - Bank 1 Sensor 2 (Downstream)
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Found the 2nd o2 sensor, and thank you for clarifying the part numbers. Mine are exact configuration as you stated, 1 before the cat, 1 right after. No mini cats, and no additional o2 sensors further upstream nor on the manifold. Thanks!
 
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I'm struggling with the NGK website trying to validate the O2 sensor part #'s. Not that I doubt the research done here, but I'd rather "trust but verify." At the same time I'm trying to figure out what the correct O2 sensor part is for a 99 Cherokee. Unfortunately I can't seem to get it to pull up any O2 sensors for the models I'm interested in (97, 99, 2002)

I see screen caps posted here but I can't seem to pull them up on the NGK parts finder.
 
hear said:
I'm struggling with the NGK website trying to validate the O2 sensor part #'s. Not that I doubt the research done here, but I'd rather "trust but verify." At the same time I'm trying to figure out what the correct O2 sensor part is for a 99 Cherokee. Unfortunately I can't seem to get it to pull up any O2 sensors for the models I'm interested in (97, 99, 2002)

I see screen caps posted here but I can't seem to pull them up on the NGK parts finder.
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Worst case scenario call NGK/NTK directly their techs are VERY helpful and they know their product. The 2000 Federal emissions TJ was not listed in their database as only having 2 sensors when I first looked. I called them direct and they knew instantly what I was after.
 
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).

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)​
​
​
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 extensions will solve the problem:

[URL][URL][URL][URL]https://www.amazon.com/dp/B06XKGVFN4/?tag=wranglerorg-20[/URL][/URL][/URL][/URL]
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What about oem part numbers like:

Mopar Oxygen Sensors

56029050aa

56029049aa

56029050aa

56028994ab

Which one is bank 1 sensor 1 ect...
 
eltavo619 said:
What about oem part numbers like:

Mopar Oxygen Sensors

56029050aa

56029049aa

56029050aa

56028994ab

Which one is bank 1 sensor 1 ect...
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Not sure, but the ones I linked to are OE sensors. NTK is the OE supplier to Mopar. You’re being ripped off if you’re buying the Mopar ones directly from a dealer.
 
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