O2 sensor replaced—wow

Because of this tread, I bought 4 new ones and replaced 3 yesterday. I couldn't get the 4th one out (bank 2, sensor 2). I can turn it a 1/4 turn, then it just locks up on me. I think there is carbon buildup on the treads on the inside. I need to soak it, or heat it, or something. I too feel as if it made a significant improvement on throttle response. Haven't driven it enough to know if it is just the placebo effect, however. I paid $152 for all four (NGK), the offset socket, the straight socket, and the Permatex Anti-Seize (they came coated with anti-seize already).
 
Aloha Joe said:
Thanks. Sorry, I should have been more clear - it sounds like it's more important on the newer TJ's to change the downstream O2 sensors and I was curious why that is.
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The downstream O2 sensors have slightly more of a role in setting the air/fuel mixture when there are pre-cats above them.
 
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anyone have the part numbers for the correct sensors, just bought bosch not knowing they were crap and want to get the ngk while i have the jeep on the ramps
 
psdtime said:
Because of this tread, I bought 4 new ones and replaced 3 yesterday. I couldn't get the 4th one out (bank 2, sensor 2). I can turn it a 1/4 turn, then it just locks up on me. I think there is carbon buildup on the treads on the inside. I need to soak it, or heat it, or something. I too feel as if it made a significant improvement on throttle response. Haven't driven it enough to know if it is just the placebo effect, however. I paid $152 for all four (NGK), the offset socket, the straight socket, and the Permatex Anti-Seize (they came coated with anti-seize already).
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Mine did the same thing. I worked at back and forth a bit with no improvement. Sprayed it with some penetrating fluid. Came back a hour later and it almost came out by hand.
 
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Finally got the 4th one out today. It must have been cross threaded. I got real lucky that the threads in the exhaust were still in good shape.

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Just ordered the upstream O2 sensor for mine. Can't wait to see if it makes a difference on how it is running! :D
 
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Ok, I changed the upstream sensor today. Took it for a drive down the street and back and it seemed to be more peppy then before, but I honestly can't say if it was the sensor that made it feel that way, or the fact that I have been driving my heavy 4 cyl PT cruiser for the last 2 days. LOL I will have to wait till I actually drive it around town to see how much of a change there is or isn't.

Here is the old one.

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Oldguy said:
If you you have mapp gas torch heat up the bung hole on the pipe. Works well and makes life easy
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He he... he said bung hole.. he he...

Jerry, could you define "older" vs "newer" TJ?

I have a 2002 with about 105k on it. It has done a lot of sitting and rusting the past few years. I am patching, replacing and spray painting as needed to keep it going just as a beater to get me off the mountain I live on in the winter down to flatlands where the roads look like the Bonneville Salt Flats. I am glad I stumbled on this article as I just assumed they would need to be replaced when a code said they were bad, not as a maintenance item.
 
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Chris said:
I always tell people, replace your O2 sensors every 80k or so. Also, DO NOT just replace one because it’s bad, replace ALL OF THEM at the same time.

People need to understand that regardless of whether they are bad or not, they are general maintenance items.
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Are all 4 the same ?
 
KCsTJ said:
I keep a brand new spare NTK 02 sensor for my 2.5L 97 with 173k in a parts inventory box👨‍🔧
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Hey, I am about to do this on my 97 2.5L as well. Any lessons you can share, other than what I’m reading on this thread?
 
My list of maintenance items grows every time I log into the forum! LOL :ROFLMAO:
I wonder if I should go though the rest of the fleet (non Jeep) and change them out...
 
KimsJeep said:
See now, I was feeling pretty good about this o2 sensor changing business. All the comments on how much it helped on this or that, then you have to go and scare me. LOL Not sure if I want to have to start "unmasking" things that are currently not known. LOL Maybe this is one of those, if its not broke, don't mess with it times. :D
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If ignorance is bliss, then we’re ecstatic. 😆
 
Jerry Bransford said:
The downstream O2 sensor mounted on the catalytic converter on older TJs rarely goes bad and its only job is to monitor the cat for proper operation. It doesn't affect how the engine runs. I'd only replace the upstream O2 sensor on those older models without the pair of precats. :)
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Interesting…in another threat I asked a guy why he was replacing all his O2 sensors instead of the one throwing the code. Everybody including you said “always change them all??? Preventive maintenance….”
 
4x4fam said:
Interesting…in another threat I asked a guy why he was replacing all his O2 sensors instead of the one throwing the code. Everybody including you said “always change them all??? Preventive maintenance….”
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A different (only two total) O2 sensor setup is used on older TJs like the one you quoted. In newer TJs all four O2 sensors, mounted just above and just below the small pre-catalytic converters, affect the engine. In older TJs like the one you quoted, only one O2 sensor affects the engine, the sole upstream sensor. The sole downstream O2 sensor, mounted on the cat, only monitors the catalytic converter and it does not affect the engine.
 
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