The Official Jeep Wrangler TJ Oxygen (O2) Sensor Thread

So after changing all 4 sensors and clearing the codes, P0133 came back last night. I'm assuming it's an issue with one of the pre-cats.

I'm having some engine shudder issues. Say I'm traveling down the road at 65 and get stopped at a red light. While I'm sitting there at a stop, sometimes the engine will shudder for a couple seconds and RPMs will drop. Not much, say 500 RPM maybe? It almost feels like it's trying to shut off, then it goes back to normal all while waiting on the light. Light turns green and drive off and everything is fine.

Are these issues related?
X2 but only on occasion. Interested to see responses to this
 
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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!

73AB1BB9-0BCF-4B3C-97FB-0DF401EBB436.jpeg


0F3F21C4-F635-4ED3-A941-5ADB534C2CFF.jpeg


B657AFC2-7E4F-4265-84D6-AD3AF9AE4B74.jpeg
 
I can't tell much from the photos but if you've only got 1 Cat and 2 sensors I'm not sure how the computer is reading that.... must have been rewired as well.

As for milage, My 05 Rubicon gets between 14.5 and 16 mpg (US). I changed O2 sensors and did plugs and coil rail after I bought it with 78K miles on it when it was getting in the mid to high 13's. TJ's don't get good milage but somewhere around 15mpg US is about all you can hope for.

Good luck. I'm sure one of the more knowledgable members will be along soon to help you on this. Welcome btw!...
 
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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

View attachment 322597
I can't tell much from the photos but if you've only got 1 Cat and 2 sensors I'm not sure how the computer is reading that.... must have been rewired as well.

As for milage, My 05 Rubicon gets between 14.5 and 16 mpg (US). I changed O2 sensors and did plugs and coil rail after I bought it with 78K miles on it when it was getting in the mid to high 13's. TJ's don't get good milage but somewhere around 15mpg US is about all you can hope for.

Good luck. I'm sure one of the more knowledgable members will be along soon to help you on this. Welcome btw!...
Export TJs didn't have to meat the same US EPA standards. In the US 2000 was the last year that Jeep used a 2 sensor setup on the 4.0 and that was for the "Federal" emissions models. The California emissions models started running the 4 sensor systems that year. I would bet your ECM is programmed the same as the Federal Emissions 2000 model year.


I think I remember someone discussing export emissions differences (maybe on this thread) but short of reading through the whole thread to find it Calling NGK/NTK directly is probably the fastest way to check if they have a listing for exports.
 
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Export TJs didn't have to meat the same US EPA standards. In the US 2000 was the last year that Jeep used a 2 sensor setup on the 4.0 and that was for the "Federal" emissions models. The California emissions models started running the 4 sensor systems that year. I would bet your ECM is programmed the same as the Federal Emissions 2000 model year.


I think I remember someone discussing export emissions differences (maybe on this thread) but short of reading through the whole thread to find it Calling NGK/NTK directly is probably the fastest way to check if they have a listing for exports.
Might have finally found the comment you were talking about…

I have both of these sensors within the package of 4 that I ordered for a 01 setup. Thanks for that info, even the Jeep mechanic here didn’t have an answer about the export differences. Will give this a crack and see how I go.

4AC7A3D9-F757-42CC-BFAE-C3F027B6B191.png
 
Might have finally found the comment you were talking about…

I have both of these sensors within the package of 4 that I ordered for a 01 setup. Thanks for that info, even the Jeep mechanic here didn’t have an answer about the export differences. Will give this a crack and see how I go.

View attachment 322636
Glad you found it. I knew it didn't use the same sensors as the '00 model and I couldn't remember the right #s.
 
Can anyone confirm if I have the banks and sensor locations right before I go at it?
Picture taken from beneath drivers side door
2005 4.0
IMG_3696 copy.jpg
 
Hi guys! Writting from Brazil. I have a 2001 TJ 4.0 Sport - love it - and a 1973 CJ5 6cil - love it.

Doing some preventive maintance, travelled to US and bought a bunch of small parts - sometimes 5x cheaper than it would cost in Brz. But made a mistake… mine hat 2 O2 sensors, not 4 of them. I bouht the:
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)

After reading these N pages I understood a should have bought the 1999 “solution”:
1997-1999
NGK #23151 - Bank 1, Sensor 1 (Upstream)
NGK #23099 - Bank 1, Sensor 2 (Downstream)

Could I use what i bought? Maybe I will need to adjust wires or plugs… not so easy to return or by new ones (NTK).

My Vin Info attachet

Thank you all for all the rich information and experiences.

best, Luiz
 

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Hi guys! Writting from Brazil. I have a 2001 TJ 4.0 Sport - love it - and a 1973 CJ5 6cil - love it.

Doing some preventive maintance, travelled to US and bought a bunch of small parts - sometimes 5x cheaper than it would cost in Brz. But made a mistake… mine hat 2 O2 sensors, not 4 of them. I bouht the:
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)

After reading these N pages I understood a should have bought the 1999 “solution”:
1997-1999
NGK #23151 - Bank 1, Sensor 1 (Upstream)
NGK #23099 - Bank 1, Sensor 2 (Downstream)

Could I use what i bought? Maybe I will need to adjust wires or plugs… not so easy to return or by new ones (NTK).

My Vin Info attachet

Thank you all for all the rich information and experiences.

best, Luiz

Those don't look like the correct numbers for the export TJ.
The author of this post had the same problem. the numbers he came up with are not the same as the 99 model.
Post #308

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good day all from South Africa

I am looking for a Upstream o2 sensor on a 1997 TJ 4l sport RHD export model

The NGK 23151 is no more manufactured according to NGK Europe

It is not available on amazone any more

what is the second best type I can try
 
good day all from South Africa

I am looking for a Upstream o2 sensor on a 1997 TJ 4l sport RHD export model

The NGK 23151 is no more manufactured according to NGK Europe

It is not available on amazone any more

what is the second best type I can try

You should be able to chat online with someone from NGK/NTK about what to use as a substitute.
 
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
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:

https://www.amazon.com/dp/B06XKGVFN4/?tag=wranglerorg-20

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!!
 
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!!

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.