Jeep TJ O2 Sensor Guide (Symptoms, Codes, Replacement & Fixes)

[macleanflood]

yes I can read and I have 1 volt constant at the downstream sensor and 25.78% trimming

Typically an O2 sensor will range under .9v.

-Mac

 

[mjonesjr84]

yes I can read and I have 1 volt constant at the downstream sensor and 25.78% trimming

Check the wiring.

 

[onechal21]

Check the wiring.

I checked I found nothing
Maybe I’ll need an engineer

 

[mjonesjr84]

I checked I found nothing
Maybe I’ll need an engineer

A split or broken wire can be hidden pretty well. My JK was at 1.0 on the volts. After I fixed the broken wires, it worked perfectly.

 

[Cloaked_TJ06]

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 the same thing as NGK and they share the same part numbers. NTK is owned by NGK, it's simply their division for O2 sensors.

4 Cylinder Engines​

​

1997-2000​

NTK #23179 - Bank 1, Sensor 1 (Upstream)​

NTK #23151 - Bank 1, Sensor 1 (Upstream) (1998 ONLY)​

NTK #23179 - Bank 1, Sensor 2 (Downstream)​

​

2001-2004​

NTK #23138 - Bank 1, Sensor 1 (Upstream)​

NTK #23141 - Bank 1, Sensor 2 (Downstream)​

​

2005-2006​

NTK #23159 - Bank 1, Sensor 1 (Upstream)​

NTK #23159 - Bank 1, Sensor 2 (Downstream)​

​

​

6 Cylinder Engines​

​

1997-1999​

NTK #23151 - Bank 1, Sensor 1 (Upstream)​

NTK #23099 - Bank 1, Sensor 2 (Downstream)​

2000 (Federal Emissions)​

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

NTK #23179 - Bank 1 Sensor 2 (Downstream)​

2000 (California Emissions)​

NTK #23179 - Bank 1, Sensor 1 (Upstream)​

NTK #23506 - Bank 2, Sensor 1 (Upstream)​

NTK #23110 - Bank 1, Sensor 2 (Downstream)​

NTK #23179 - Bank 2, Sensor 2 (Downstream)​

2001-2003​

NTK #23139 - Bank 1, Sensor 1 (Upstream)​

NTK #23138 - Bank 2, Sensor 1 (Upstream)​

NTK #23142 - Bank 1, Sensor 2 (Downstream)​

NTK #23141 - Bank 2, Sensor 2 (Downstream)​

​

2004​

NTK #23137 - Bank 1, Sensor 1 (Upstream)​

NTK #23135 - Bank 2, Sensor 1 (Upstream)​

NTK #23132 - Bank 1, Sensor 2 (Downstream)​

NTK #23531 - Bank 2, Sensor 2 (Downstream)​

​

2005-2006​

NTK #23018 - Bank 1, Sensor 1 (Upstream)​

NTK #23160 - Bank 2, Sensor 1 (Upstream)​

NTK #23159 - Bank 1, Sensor 2 (Downstream)​

NTK #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 O2 sensor extensions will solve the problem.

Hey Chris , I came across this thread because my 2006 TJ 4.0l has a code I think for an O2 sensor which is P0137 which sensor is that ? also I noticed my CEL would leave then come back on and so on any ideas ?

 

[Chris]

Hey Chris , I came across this thread because my 2006 TJ 4.0l has a code I think for an O2 sensor which is P0137 which sensor is that ? also I noticed my CEL would leave then come back on and so on any ideas ?

The P0137 code indicates a problem with the downstream O2 sensor (Bank 1, Sensor 2). This code most likely means that the sensor is reading a low voltage, which can be caused by a faulty sensor, wiring issues, or even a problem with the exhaust system itself.

If your check engine light (CEL) is intermittent, it might suggest a connection issue, or the O2 sensor could be marginally functioning. Here are a few steps to troubleshoot:

• Check for any damaged wires or loose connections to the O2 sensor. A break or short in the wiring can cause intermittent signals. Sometimes breaks in the wiring can be very, very difficult to track.
• If the wiring looks good, consider replacing the downstream O2 sensor with a NGK/NTK sensor (if you can still find one), as those are known to work best with TJs.
• Inspect the exhaust system for any leaks before the O2 sensor. An exhaust leak can also affect sensor readings and may trigger the CEL.
• After you’ve checked and possibly replaced any faulty parts, clear the code and see if it comes back.

 

[hardtailpan]

• If the wiring looks good, consider replacing the downstream O2 sensor with a NGK/NTK sensor (if you can still find one), as those are known to work best with TJs.

Chris, for whatever reason, RockAuto seems to have all of the NTK sensors for our TJs in stock now. Hopefully they are still of the same quality as I just ordered 4 for an 02 Apex.

 

[Chris]

Chris, for whatever reason, RockAuto seems to have all of the NTK sensors for our TJs in stock now. Hopefully they are still of the same quality as I just ordered 4 for an 02 Apex.

Should be good to go! I don’t think the supply has fully dried up just yet.

 

[hardtailpan]

Should be good to go! I don’t think the supply has fully dried up just yet.

Good. I've got the driveline out for a motor/trans swap and I'd like to do all 4 while they are easy to get at. At the very least I'll break em' all free and antisieze the ones that are in there before I put the motor back in just in case they are no good.

 

[Cloaked_TJ06]

The P0137 code indicates a problem with the downstream O2 sensor (Bank 1, Sensor 2). This code most likely means that the sensor is reading a low voltage, which can be caused by a faulty sensor, wiring issues, or even a problem with the exhaust system itself.

If your check engine light (CEL) is intermittent, it might suggest a connection issue, or the O2 sensor could be marginally functioning. Here are a few steps to troubleshoot:

• Check for any damaged wires or loose connections to the O2 sensor. A break or short in the wiring can cause intermittent signals. Sometimes breaks in the wiring can be very, very difficult to track.
• If the wiring looks good, consider replacing the downstream O2 sensor with a NGK/NTK sensor (if you can still find one), as those are known to work best with TJs.
• Inspect the exhaust system for any leaks before the O2 sensor. An exhaust leak can also affect sensor readings and may trigger the CEL.
• After you’ve checked and possibly replaced any faulty parts, clear the code and see if it comes back.

Hey Chris , I replaced the o2 sensor with a Walker o2 sensor yesterday but the p0137 code came back on plus a p2096 where is that located and what bank and sensor is that ? also what Is the OEM O2 sensors I should get from my local orileys ?

 

[Chris]

Hey Chris , I replaced the o2 sensor with a Walker o2 sensor yesterday but the p0137 code came back on plus a p2096 where is that located and what bank and sensor is that ? also what Is the OEM O2 sensors I should get from my local orileys ?

The P2096 code indicates that the post-catalytic converter O2 sensor (Bank 1, Sensor 2) is detecting a fuel trim issue, specifically that it is indicating a lean condition. Since you just replaced the downstream O2 sensor and the code returned, it might be worth double-checking the following:

• Make sure there's no damage or corrosion in the wiring or connectors for both the downstream O2 sensor and the upstream sensor. Can't stress this one enough! Often damage to the wiring can be very difficult and time consuming to locate.
• Inspect the exhaust system for any leaks between the catalytic converter and the downstream O2 sensor. An exhaust leak can cause incorrect readings.

I would run any other sensors other than NGK / NTK or Walker. To my knowledge (and I could be wrong) those are the only ones that aren't known to cause issues with reoccurring codes and such.

 

[macleanflood]

I replaced my O2 downstream with a Walker the other day too. DOA. Pure trash.

Rock Auto gamble and lost...

For reference it was part 25024942.

-Mac

 

[mjonesjr84]

I replaced my O2 downstream with a Walker the other day too. DOA. Pure trash.

Rock Auto gamble and lost...

For reference it was part 25024942.

View attachment 627494

-Mac

That's crazy. I have had great luck with Walker in my TJ & JK.

 

[macleanflood]

That's crazy. I have had great luck with Walker in my TJ & JK.

Auto parts store guy suggested my O2 bung might be too close to my cat. That would explain others...but this one was 1v from the get go and my original was .9v. Also getting heater codes now too.

Everyone can make a dud. At least this one isn't as consequential as a dud 5" display shell.

-Mac

 

[macleanflood]

Realized I had a solution for my O2 sensor issue all along...rusted out 2000 Sahara. Harvested the rear O2 sensor...NGK oza348-c1 and bingo! We have ranging voltage. Now the long term question of it being 3" from my cat. Wondering if I should order a plug and another bung and get it closer to my muffler.

That's the new walker, the used NGK covered in black spot and my original all tan colored for reference.

-Mac

 

[Cloaked_TJ06]

The P2096 code indicates that the post-catalytic converter O2 sensor (Bank 1, Sensor 2) is detecting a fuel trim issue, specifically that it is indicating a lean condition. Since you just replaced the downstream O2 sensor and the code returned, it might be worth double-checking the following:

• Make sure there's no damage or corrosion in the wiring or connectors for both the downstream O2 sensor and the upstream sensor. Can't stress this one enough! Often damage to the wiring can be very difficult and time consuming to locate.
• Inspect the exhaust system for any leaks between the catalytic converter and the downstream O2 sensor. An exhaust leak can cause incorrect readings.

I would run any other sensors other than NGK / NTK or Walker. To my knowledge (and I could be wrong) those are the only ones that aren't known to cause issues with reoccurring codes and such.

Is there a reason why I have both codes but its the same bank 1 sensor 2 ?

 

[Chris]

Is there a reason why I have both codes but its the same bank 1 sensor 2 ?

Yes, having both the P0137 and P2096 codes is actually not uncommon since they refer to related issues with the same sensor—specifically the downstream O2 sensor (Bank 1, Sensor 2).

The P0137 code indicates that your downstream O2 sensor is reading a low voltage, which suggests it's not functioning correctly. The P2096 code, on the other hand, points to a fuel trim issue indicating a lean condition, which can also be a consequence of the faulty O2 sensor not responding as it should.

In essence, the downstream O2 sensor plays a critical role in the vehicle's fuel management system, and if it isn’t working properly, it can cause both erroneous readings and fuel trim issues. It’s like a domino effect.

 

[Cloaked_TJ06]

Yes, having both the P0137 and P2096 codes is actually not uncommon since they refer to related issues with the same sensor—specifically the downstream O2 sensor (Bank 1, Sensor 2).

The P0137 code indicates that your downstream O2 sensor is reading a low voltage, which suggests it's not functioning correctly. The P2096 code, on the other hand, points to a fuel trim issue indicating a lean condition, which can also be a consequence of the faulty O2 sensor not responding as it should.

In essence, the downstream O2 sensor plays a critical role in the vehicle's fuel management system, and if it isn’t working properly, it can cause both erroneous readings and fuel trim issues. It’s like a domino effect.

So pretty much what im getting out of this is replace the o2 sensor with an ntk OEM one instead of the Walker on I have in it currently then it should fix my issues of the 2 codes for that one o2 sensor ?

Also off topic here but i put in a proposition valve not too long ago and I still have the brake light indicator come on na d when I step on the brake it goes of then it'll come back on and so on . My brake fluid is full also that prop valve came from amazon because I wasn't spending $300 or so on a mopar one . don't know if my issue is that I didn't get OEM or not but I would love for it to go away and stop beeping all the time annoys the crap out of me . especially when i stop then go again is when it loved to turn on and flash . its hard to explain but that's what I keep seeing . I would've made another post about this but felt like it was fitting here with my other issues I'm having so I can read it all on one writeup

 

[Chris]

So pretty much what im getting out of this is replace the o2 sensor with an ntk OEM one instead of the Walker on I have in it currently then it should fix my issues of the 2 codes for that one o2 sensor ?

Also off topic here but i put in a proposition valve not too long ago and I still have the brake light indicator come on na d when I step on the brake it goes of then it'll come back on and so on . My brake fluid is full also that prop valve came from amazon because I wasn't spending $300 or so on a mopar one . don't know if my issue is that I didn't get OEM or not but I would love for it to go away and stop beeping all the time annoys the crap out of me . especially when i stop then go again is when it loved to turn on and flash . its hard to explain but that's what I keep seeing . I would've made another post about this but felt like it was fitting here with my other issues I'm having so I can read it all on one writeup

Walker should be fine, it might actually be a wiring issue as it so often is.

Make another post for the other issue.

 

[macleanflood]

Walker should be fine, it might actually be a wiring issue as it so often is.

Make another post for the other issue.

Yup I'm running Walker on my F250 zero issues. I just got a bad one out of the box. Probably not worth arguing with Rock Auto.

Do start a new thread. Consider that the common denominator of both of your issues is wiring and grounds.

-Mac