The Official Jeep Wrangler TJ Oxygen (O2) Sensor Thread

The cat has a code.
That makes more sense. As inexpensive as they are it wouldn't hurt to replace them, but I don't think it would be necessary. Lots of people replace them as preventative maintenance, although I am not one of those people. IIRC they do have a scheduled replacement interval, you could find that in the FSM.
 
Thanks to Chris and others in this tread. I changed the senosors today in about 45 minutes. The original ones came out a lot easier than I expected. The downstream Bank 2 one was the only one with a little difficulty as the wire connection is in a hard to reach area.

I wasn't having any codes and the Jeep has about 75K on it but my mileage has been crappy so I did the plugs and now the sensors. The mileage jumped about 1.5MPG after the plugs and I'm hoping to get that .5 to 1 back to get to the EPA numbers.
 
A little more info, my Jeep has over 225,000 miles and I have no idea if it when the O2 sensors have ever been changed and if they were what backs I was used. I'm changing the bad cat anyway, is there a way to see if they are OE or an acceptable brand when I pull them? Should I just change them so I know what they are and how old they are?
 
A little more info, my Jeep has over 225,000 miles and I have no idea if it when the O2 sensors have ever been changed and if they were what backs I was used. I'm changing the bad cat anyway, is there a way to see if they are OE or an acceptable brand when I pull them? Should I just change them so I know what they are and how old they are?
I'd change them out if you don't know when they were done. All 4 cost a little over $100. Use the NTK part numbers Chris put in the first post in this thread. The success with other brands is spotty while the NTK ones work great.
 
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Hi folks. I have a 2000 Wrangler 4.0. But I have a Y and one 02 sensor before the single catalytic converter. It has 4 wires. And the sensor you recommend has five wires and the diagram shows two sensors I'm so confused.
 
Hi folks. I have a 2000 Wrangler 4.0. But I have a Y and one 02 sensor before the single catalytic converter. It has 4 wires. And the sensor you recommend has five wires and the diagram shows two sensors I'm so confused.
The 2 sensors you need for the "Federal Emissions" 2000 4.0l are,
NTK 23122 (upper) before the cat
NTK 23099 (lower) after the cat
 
The 2 sensors you need for the "Federal Emissions" 2000 4.0l are,
NTK 23122 (upper) before the cat
NTK 23099 (lower) after the cat
Thanks ! I hope this solves my P0171 problem. As I cant find any vacuum leaks and I have replaced my MAP sensor. I have a new remanufactured motor that ran fine for a month. I also squirted some starting fluid around the intake and exhaust gasket and nothing seems to change.
 
Thanks ! I hope this solves my P0171 problem. As I cant find any vacuum leaks and I have replaced my MAP sensor. I have a new remanufactured motor that ran fine for a month. I also squirted some starting fluid around the intake and exhaust gasket and nothing seems to change.
I'm not very familiar with what causes the P0171, other than a vacuum leak, with our Jeeps. (I haven't experienced that code on my '00 yet.) There are lots of hard to reach places we can develop vacuum leaks, including right at the firewall, inside the dash or even along the frame rail all the way back to the fuel tank. You might try searching that specific code on the forum, if you already haven't. I know there have been quite a few members that have battled vacuum leaks on here.
 
I'm not very familiar with what causes the P0171, other than a vacuum leak, with our Jeeps. (I haven't experienced that code on my '00 yet.) There are lots of hard to reach places we can develop vacuum leaks, including right at the firewall, inside the dash or even along the frame rail all the way back to the fuel tank. You might try searching that specific code on the forum, if you already haven't. I know there have been quite a few members that have battled vacuum leaks on here.

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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)​
Six months ago I probably should have replaced all four of those but I only replaced 23159 to fix P0136 (or P0138, I don't quite remember).​
Two days ago I got P0153 so I need 23160 to fix that and I also ordered 23018 and 23158 so I don't have to worry about any of those.​
Here's an example where O2 sensors get weird in general:​

In my Dodge Ram I've had P0420 and P0152 for a while and ordered both O2 sensors needed for Bank 1. What O2 sensors are they?​

NGK #23160 - Bank 1, Sensor 1 (Upstream)
NGK #23159 - Bank 1, Sensor 2 (Downstream)

And what if I needed the sensors for Bank 2?

NGK #23160 - Bank 2, Sensor 1 (Upstream)
NGK #23159 - Bank 2, Sensor 2 (Downstream)​
23159 follows 23160 no matter what bank they are on but they're not on the same bank of the 4.0​


 
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There is so much great info here. I just bought a used 2005 LJ 4.0 with 93,000 and after the first 200 miles I've driven it, I'm getting P2096 and P2098 codes. I have a feeling the seller cleared the codes before I test drove it.

It seems to be running OK. Looks like I'm going to try replacing all 4 O2 sensors.

I've got the NGK part numbers Chris provided above, but I also see references to NTK sensors in the threads.

Are the NTKs made by NGK and does the 4.0 like them?? When I search for the NGK part number on Amazon only NTK sensors show up. Should I only buy NGK sensors?

Thanks again for the support!
 
There is so much great info here. I just bought a used 2005 LJ 4.0 with 93,000 and after the first 200 miles I've driven it, I'm getting P2096 and P2098 codes. I have a feeling the seller cleared the codes before I test drove it.

It seems to be running OK. Looks like I'm going to try replacing all 4 O2 sensors.

I've got the NGK part numbers Chris provided above, but I also see references to NTK sensors in the threads.

Are the NTKs made by NGK and does the 4.0 like them?? When I search for the NGK part number on Amazon only NTK sensors show up. Should I only buy NGK sensors?

Thanks again for the support!
NTK is the NGK heading for their O2 sensors, so you're good!!
 
Thank you! Now the fun begins getting those suckers out! I'm in the rustbelt of NE Ohio and they may never have been replaced!!

Soak them with a petroleum penetrating lubricant about 2 hours or so before you try and remove them.

I'm lucky where I live.... at nearly 80K they came out without any problem but I've read a few accounts here of people having a heck of a time getting them to break free.
 
So I just changed out all 4 sensors on my 2005 4.0. Went super smoothly and although I bought the special socket wrench, didn’t use it. Was much easier to do it with an open end wrench.

However, I have now developed a small exhaust leak right at the 1,1 O2 sensor. I can hear it and literally feel the air pushing out right in that area. Any possibility that the sensor is the culprit or am I most likely looking at a bad flange? I’ll diagnose a little more this morning but thought I would pop in here and ask. It’s throwing a code and the motor is definitely running a tad rough.
 
So I just changed out all 4 sensors on my 2005 4.0. Went super smoothly and although I bought the special socket wrench, didn’t use it. Was much easier to do it with an open end wrench.

However, I have now developed a small exhaust leak right at the 1,1 O2 sensor. I can hear it and literally feel the air pushing out right in that area. Any possibility that the sensor is the culprit or am I most likely looking at a bad flange? I’ll diagnose a little more this morning but thought I would pop in here and ask. It’s throwing a code and the motor is definitely running a tad rough.

Definitely not the sensor. Either the flange or a rotted section of exhaust.