The Official Jeep Wrangler TJ Oxygen (O2) Sensor Thread

Yea, I just found it odd that the leak would develop right after I swapped out the plug. Any idea how tight the exhaust flange bolts need to be snugged?

I don’t know the torque specs, but they are in the FSM.

If you were down there wrenching on the exhaust, it stands to reason if it’s old and worn enough, the force could have caused an area to crack.
 
Just did this last week. Easier to pull the skid plate off first. Disconnect the O2 sensors, pull two nuts off the muffle flange, pull the 4 header flange bolts. I found a gear wrench worked great for getting off the header flange bolts rather than trying to use a socket and a u joint.
 
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I don’t know the torque specs, but they are in the FSM.

If you were down there wrenching on the exhaust, it stands to reason if it’s old and worn enough, the force could have caused an area to crack.

Pulled the bolts and then reset the flange and tightened it all up. Leak is gone and Jeep runs great with the new 02 sensors. But half hour later, my newly installed heater core blew up and I discovered that my Transfer Case won't shift back into 2wd (probably because of the body lift) :mad:. Thank God I have a run coming up in 4 days :ROFLMAO:
 
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Pulled the bolts and then reset the flange and tightened it all up. Leak is gone and Jeep runs great with the new 02 sensors. But half hour later, my newly installed heater core blew up and I discovered that my Transfer Case won't shift back into 2wd (probably because of the body lift) :mad:. Thank God I have a run coming up in 4 days :ROFLMAO:

Damn, the heater core blew up? I had that happened to me once on an older VW from the 90s. My leg got burned from all the hot coolant!
 
It wasn’t that bad. I had just cleaned and sealed the box up pretty nice so the majority of the pressure went out the vent into the engine compartment. Was alarming though.
 
Just did this last week. Easier to pull the skid plate off first. Disconnect the O2 sensors, pull two nuts off the muffle flange, pull the 4 header flange bolts. I found a gear wrench worked great for getting off the header flange bolts rather than trying to use a socket and a u joint.

How long did it take you?
 
Maybe 2.5-3 hours start to finish. Would have been less if I haven’t broken a bolt on the muffler flange.
 
2005 4.0 Auto Unlimited Rubicon 116K.

Got the P2096 and P2098 codes, so I replaced all 4 with NTK from Rock Auto.

Disconnected the battery to clear the codes, after a trip to town 40 miles one way I was almost back and the CEL came on with P2096 and P2098 codes.

Disconnected the battery and cleared the codes, but CEL came back on with the same P2096 and P2098 codes.

My ECU was replaced by the PO @ 85k with a MOPAR factory unit.

What is the next step to do to keep them from coming back?
Thanks
 
Had the same issue with my 05, the bolts holding the manifold onto the engine were loose, the sensors were fine! The top bolts are a shit to get to but you can do it..
 
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2005 4.0 Auto Unlimited Rubicon 116K.

Got the P2096 and P2098 codes, so I replaced all 4 with NTK from Rock Auto.

Disconnected the battery to clear the codes, after a trip to town 40 miles one way I was almost back and the CEL came on with P2096 and P2098 codes.

Disconnected the battery and cleared the codes, but CEL came back on with the same P2096 and P2098 codes.

My ECU was replaced by the PO @ 85k with a MOPAR factory unit.

What is the next step to do to keep them from coming back?
Thanks

It's very likely you have a short in the wiring somewhere.
 
Great thread.. thanks to all the contributers!

having an issue with 06 4L manual.. currently 81K miles.. replaced all 4 O2 sensors about 4 years ago with NTKs Have done about 10K miles since (it’s not a daily) and now it is throwing codes again.. 2 weeks ago P2096.. bank1 sensor 2. Reset PCM and now today is has thrown P0133 bank 1 sensor 1.. Have no codes for bank 2 (yet)

Questions are

1. How long either age or miles are these supposed to last.
2. If an O2 sensor is bad.. is it supposed to continually through the same code?
3. Assuming the O2 sensors are good.. what other issues could cause both up and down stream codes to trip.

Thanks in advance

MK
 
1. How long either age or miles are these supposed to last.

There is no solid answer to this, but they are a wear and tear maintenance item and should be replaced around every 80k mikes or so.

2. If an O2 sensor is bad.. is it supposed to continually through the same code?

Generally it will, yes.

3. Assuming the O2 sensors are good.. what other issues could cause both up and down stream codes to trip.

Bad cats or a short in the wiring.
 
Ok where is the G105 ground located?

Thanks

O2 Ground.JPG
 
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After dealing with a minor rear locker problem, I'm about to enter code reduction mode. Bought a nice TJR last February. Emissions was passed for 2 years. Has always run smoothly and still does, but was only getting 12 mpg when first purchased. Using tricks I learned from my exhaust sniffer (pre code days) XJ I've been able to get it up to 16-17 including several hours of low range wheeling a couple weeks ago around Crested Butte and Aspen. With each gain in fuel efficiency It throws ever more codes. Liberal government working for us! Right now, 0421 and 0058. Need to add an O2 sensor extension cable for Bank 2 downstream. That connector resides high up on bell housing making it a PITA and shoulder to disconnect. Removed that O2 sensor. Had 1/8 inch of crud on probe and couldn't even see the port slots, but didn't throw any codes. Cleaned it up then, voila! Up pops 0058. Certain parts are on order. Will update when I install expecting to stop the 0421 code as well. I've got 18 months before the State says no.
 
I figured out why I'm getting a catalytic converter CEL!

View attachment 195317View attachment 195318
That would do it. I just finished replacing g the CAT’s last night. I recommend going Magnaflow (the $372) option if you can’t get those, then Bosal from rock auto. Is a re-branded Magna down to the warranty card in the box

whatever you do don’t get Eastern Catalytic. You can look at my build thread for the headache I had there.