The Official Jeep Wrangler TJ Oxygen (O2) Sensor Thread

I'll swap the thermostat


I did notice on the Torque Pro app that the coolant temp would drop to around 175*F when ideling and around the same time the CEL came on for the P0420.

I'll swap the current thermostat out for a 195*F one later this week when I get it back from the shop getting the lift installed and see what it does with the code. Hopefully that fixes the issue.

It's plausable, the engine not warming up enough could an overly rich condition which can contribute to inefficiency in the Cat.... I'm still leaning towards your cat not getting hot enough to work as the cause of your code.
 
It's plausable, the engine not warming up enough could an overly rich condition which can contribute to inefficiency in the Cat.... I'm still leaning towards your cat not getting hot enough to work as the cause of your code.

What would be the solution to a catalytic converter not getting hot enough? Would it be a bad cat?
 
What would be the solution to a catalytic converter not getting hot enough? Would it be a bad cat?

If your engine isn't warming up properly it's not going to burn the fuel as efficiently (exhaust would be heavy with unburned fuel = cold exhaust) . When the cat heats up it helps burn off that unburned fuel.. Again the code comes back as the cat is not working as it should...

I would try the thermostat first and see if it solves the problem. If not then you might research some catalytic converter "cleaners" and give that a try... Which bank is the code being thrown on?
 
If your engine isn't warming up properly it's not going to burn the fuel as efficiently (exhaust would be heavy with unburned fuel = cold exhaust) . When the cat heats up it helps burn off that unburned fuel.. Again the code comes back as the cat is not working as it should...

I would try the thermostat first and see if it solves the problem. If not then you might research some catalytic converter "cleaners" and give that a try... Which bank is the code being thrown on?

Will do.

It is only throwing on Bank 1. I do have the CA emissions.
 
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Will do.

It is only throwing on Bank 1. I do have the CA emissions.

That's why I asked what bank it was... Bank 1 sensor 2 p0420... One other thing to check would be make sure there are no exhaust leaks on that bank before the cat or after the cat but before the down stream sensor (sensor #2).
 
That's why I asked what bank it was... Bank 1 sensor 2 p0420... One other thing to check would be make sure there are no exhaust leaks on that bank before the cat or after the cat but before the down stream sensor (sensor #2).

I'll check that. It doesn't sound or smell like any leaks, but it never hurts to check.
 
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For anyone doing this in the future - for my 2006 with the NGK O2 sensors listed in the first post I did not need extension cables.

I found the TEKTON O2 sensor socket tool recommended in the first post to be useless. I ended up using a 22mm box-end wrench which worked far better for me.

Andy
 
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For anyone doing this in the future - for my 2006 with the NGK O2 sensors listed in the first post I did not need extension cables.

I found the TEKTON O2 sensor socket tool recommended in the first post to be useless. I ended up using a 22mm box-end wrench which worked far better for me.

Andy

I think you'll find you're not the first to post something similar and you definitely wont be the last to find out a wrench is the only way.

Star Wars Disney Plus GIF by Disney+
 
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Got codes 0161 and 0158 this morning along with the major evap leak code. I had left my gas cap at the station and didn’t realize for a few days. Have a cap on there now just wondering if that would cause the 02 sensor codes or not.
 
Hey All

Just purchased my TJ not long ago and got a CEL. Downstream O2 sensor (Bank2 Sensor 2), its a California emissions Jeep. I tested and verified that the sensor has a open circuit.

On this forum I came across a number of threads saying that we need to stick to NGK / NTK Sensors. However I also noticed that those threads were at least 6 - 7 years old. The issue is that it looks like no one is keeping NGK sensors in house or able to ship.

My questions:
- Are there any brands that may work well now days as opposed to NGK/NTK or MOPAR?

-If not, where is the best place to source one of the NGK/NTK?
 
Hey All

Just purchased my TJ not long ago and got a CEL. Downstream O2 sensor (Bank2 Sensor 2), its a California emissions Jeep. I tested and verified that the sensor has a open circuit.

On this forum I came across a number of threads saying that we need to stick to NGK / NTK Sensors. However I also noticed that those threads were at least 6 - 7 years old. The issue is that it looks like no one is keeping NGK sensors in house or able to ship.

My questions:
- Are there any brands that may work well now days as opposed to NGK/NTK or MOPAR?

-If not, where is the best place to source one of the NGK/NTK?

Rockauto. Andy
 
Hey All

Just purchased my TJ not long ago and got a CEL. Downstream O2 sensor (Bank2 Sensor 2), its a California emissions Jeep. I tested and verified that the sensor has a open circuit.

On this forum I came across a number of threads saying that we need to stick to NGK / NTK Sensors. However I also noticed that those threads were at least 6 - 7 years old. The issue is that it looks like no one is keeping NGK sensors in house or able to ship.

My questions:
- Are there any brands that may work well now days as opposed to NGK/NTK or MOPAR?

-If not, where is the best place to source one of the NGK/NTK?

There were NTK on rock auto when I looked this morning
 
Put new NTK sensors in yesterday. Took it for a couple of test drives, all good. Engine feels smooth. Today I went for a third drive and now I have P0133 (slow response from B1S1). Sigh.

From research on the forum it seems anecdotally it could be broken pre-cats. Looking at Rockauto I would need to spend $700+tax (may as well replace the rear cat at the same time) unless I go with the generic sounding "original performance", This is not exactly a cheap repair so is there a way to diagnose the problem further?

When I replaced the O2 sensors I did put my endoscope into one of the bungs, and I could see the internal structure, but I couldn't really make sense of it, if it was OK or broken and at right-angles.

Thinking about putting the old B1S1 sensor back in to see if that solves the problem, hoping that particular sensor wasn't the cause of my random misfire and rich running.

Andy
 
Hey All

Just purchased my TJ not long ago and got a CEL. Downstream O2 sensor (Bank2 Sensor 2), its a California emissions Jeep. I tested and verified that the sensor has a open circuit.

On this forum I came across a number of threads saying that we need to stick to NGK / NTK Sensors. However I also noticed that those threads were at least 6 - 7 years old. The issue is that it looks like no one is keeping NGK sensors in house or able to ship.

My questions:
- Are there any brands that may work well now days as opposed to NGK/NTK or MOPAR?

-If not, where is the best place to source one of the NGK/NTK?

Have you read any of this thread at all?

There are a couple posts a page or two back that mention 2 different brands that people, thus far, have had good luck with.
 
That's why I asked what bank it was... Bank 1 sensor 2 p0420... One other thing to check would be make sure there are no exhaust leaks on that bank before the cat or after the cat but before the down stream sensor (sensor #2).

Since changing the thermostat, I've had the code pop up 1 time in a week. I cleared it and it hasn't came back, yet. The engine does run 195-205° consistently since the thermostat change.
 
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Had a random P0138 that’s been popping up and now won’t go away even when cleared. The truck just rolled over 44k miles and after checking the code out seems to point to the O2 sensors. I looked around on Amazon and couldn’t find any sensors listed made by NGK/NTK that “will fit” so I found the Denso brand ones here and here. I’m hoping this will solve my problem but if anyone has any other recommendations to try alongside this I’m all ears!