O2 Sensor Accessability

OK, I searched but could not find this info. Probably it is out there, but I will just ask again:

How accessible are the O2 sensors? The down streams are easy from what I read so far, is that so? But I found no info on replacing the upstreams and Haynes and Chiltons are silent on it. They just say take out the old and put in the new. Like all auto work is that easy? Come on!

On the Dakota 4.7 V8 the downstreams are easy. The upsteams are really hard unless you do it the real shop method: remove front tire, pop out the plastic rivets holding in the wheel well liner, pull out the liner, and bingo! Easy peasy to reach the sensors!

How so on the KJ?

Both upper ones can be a bit harder but not impossible
Getting the clips off for the wiring is the hardest part
Only changed out about a dozen or so of the uppers on various years of KJs and never ran into one that I would say was hard or required removing a lot of other parts
Chiltons and Haynes are ok for sort of a quick look
I have a full set of the factory Jeep service manuals for 02-03-04-05 and they show in detail, plus most were used in dealerships so some even have notes the Tech's wrote in , great resource ones to have

I agree. The hardest part is probably the wiring so you don’t break the clip. Once that’s done it’s not a real hard job. It can be a bit of a pain to get at them but not bad.

Just remember to use the proper sensors (brand). If you don’t you’ll be doing the job again soon.

Brand Recommendation...

LibertyTC said:

Brand Recommendation...

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Yep. That is what I installed on the XJ and the Dakota 4.7.

The left side rear is a pain and required me to use a o2 sensor socket upside down with a long extension and a breaker bar to replace. The upper two on the early models are almost at the exhaust manifolds. You have to get at the wiring from the front of the engine but you have to physically remove the sensors from the bottom and under. The front left drivers side is particularly a pain. But you can access it with a stubby ratchet blindly. Took me about 2.5 hours to do all 4 after extensive penetrating oil soaking - use liquid wrench, it’s the best.

I think the newer style cats have the front o2 sensors further downstream and are more accessible. Anyways the ntk are not expensive on rockauto and generally o2 sensors are a worthwhile part to replace


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Aero Kroil is the best penetrating oil, can't beat it, great stuff

But even the earlier models that are somewhat up further are not that hard IMO
Changed them on every model year except 07s

Agreed, 2.5 hours to do all four means they went easily... usually it’s 2.5 hours per sensor at best.


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I just did driver's rear the other day; penetrant soak (PB blaster) plus lots of propane torch heat at the bung finally got it to bust free, after it nearly rounding over the flats.

sota said:

I just did driver's rear the other day; penetrant soak (PB blaster) plus lots of propane torch heat at the bung finally got it to bust free, after it nearly rounding over the flats.

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Eek. Really hard to get at that one so I suppose I was lucky


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Bank 2,1 was a beast for me. I had to remove the Cat and used a torch to get it out.
Buy lower gasket, clamp & bolts needed. NGK with anti-seize. Change both Bank x,1, x,2 at the same time.