coffeechick

Okay, here I go again. 95, 4.0, don't know what else you might need to know.

Ran into a couple of instances of the CEL coming on, usually after driving for a bit. And, since the first guy at AutoZone I asked said that pre-96 couldn't ever be scanned, I just wrote them off as being completely unhelpful, and came back here to find the method described in multiple posts.

Took a couple of tries, but we got 12 and 21.

12 was not a surprise. 21 led me back here again, to see if I could narrow it down.

Obviously, it has something to do with the O2 sensor. However, I would like to know if there's something I should check first, and what I might be in for in replacing the part. Or parts.

Also, I'd like to know if I'm running any risk by using the Jeep with this problem not-fixed.

Let me know if you need anything else. I can probably even go out and get a video of the CEL flash sequence after the sun goes down [for visibility purposes] if anyone wants to verify that.

Crash_Course

On a high mileage jeep (or anything, for that matter) if there's even a shadow of a doubt about the O2 sensor and it's precise age is unknown, replace it. I replaced mine when I brought the jeep home and it cleared up several issues right away.

Replacement is really straightforward.

Radi

Check the sensor wiring too, that can also set that code.

extrashaky

Replacing an O2 sensor is pretty straight-forward. The last one I replaced literally took five minutes.

The auto parts stores will often try to sell you a generic replacement sensor for cheaper. Instead, get the stock sensor if you can, because the generic sensors require you to cut off the stock connector and splice in a different one. It works just fine, but it takes longer, and then you can't go back to the stock sensor without wiring the original connectors back in.

Be sure to use anti-seize compound on the threads when you install the new one. The last O2 sensor I bought actually came with a little tube of anti-seize.

The biggest challenge is likely to be getting the old one off. Use the correct size wrench (NOT an adjustable wrench) to avoid rounding it off. If it won't budge, hit it with PB Blaster and let it soak. They sell O2 sensor sockets that are slotted to let the wire through, but don't bother with that because you really don't need it. It's actually easier to put a wrench directly on it than to use a socket on a ratchet.

coffeechick

Recommended part numbers?

Hopefully, it hasn't been replaced before, so I'm not facing some splicing game.

salad

Original manufacturer is NTK. Not sure what a '95 uses but there should only be a single NTK part listed.

extrashaky

RockAuto.com shows the following for a '95 4.0L:

NTK upstream part number 23023
$27.89

NTK downstream part number OZA527E36
$85.79 (ouch!)

Do you know which sensor you need? If not, based on those prices you might start with the upstream sensor and see if that works, then replace the downstream sensor if it doesn't. The upstream sensor is really the more important of the two anyway.

If you search Rock Auto's site you'll see they list several other brands in addition to the NTKs, but the prices on the NTKs are right in line with the other manufacturers. The search list will show "OE style" next to the sensors that have the OE connectors. It also show little hearts next to the parts that are user-recommended.

If you can't wait a couple of days for it or would just rather buy it locally, just make sure you specify OE style when you ask for the sensor. When you get it home, reach up under there and compare the connectors. If it's not the same, take it back.

coffeechick

Thanks. Wasn't sure about which brands were okay and which ones weren't.

I was just out there with my FSM--yes, I have one, and yes, I'm terrible at understanding it fully--trying to track down the offending part. I may or may not have, depending on whether or not I have to crawl under the Jeep to do it, even for the 'upstream' one.

Assuming I found at least the 'upstream' one, it certainly looks like it's the standard variety and not a spliced-in one, so it's probable that it's never been replaced.

Edit:

Okay. Didn't go back out there, because I've done all the physical damage I want to do today. What I ended up doing was checking my library's website, where I found that they'd updated their online offerings to include, amazingly enough, automotive repair. I did not expect that, because that library is quite the fancy place. The library I used to use as a teen has it, and I've been working with my parents to work my way back into that state's library system, just so I'd have yet another resource to turn to.

With careful cross-referencing, I'm now pretty sure I located the actual part.

Now I'm wondering exactly how essential the 'tighten to 22 ft lbs torque' is. Yes, I still need to buy a torque wrench. I know I'll need one eventually, I just haven't been able to yet.

tracyk

Guessin from your name that you are of the "fairer sex" (as am I), i could not budge my frickin O2 sensors even after getting ***** stuck under stuff under the xj. I took the sensors to a shop and they charged me $40 to put them in. Given frustration/crying equation, it was $ well spent. My point: if it'll fix the prob, just delegate the task. Know you'll get it next time.

SeriousOffroad

Rogue4x4

Please tell us your jeep is lifted 9 inches, LOL


BTW, kudos to you coffechick, for getting a FSM...most guys don't even get one, LOL...IMHO, it is the best tool you'll ever buy for your XJ

tjwalker

1. You only have one oxygen sensor on your 95 which is OBDI.

2. Use ONLY NTK oxygen sensors. Other sensors are hit and miss with a whole lot of miss!

3. Read the FSM for tips on replacing if you're doing it yourself. Otherwise, a shop "shouldn't charge you that much, but be darn sure if you take it to a shop that they use NTK brand sensor.

Good luck!

s346k

check engine light? what's that ? I removed that bulb 2 years ago.

coffeechick

Yes. Yes I am. And I know I'm a bit on the weak side, too, so I never work on the thing alone. Even if I were strong enough to work things lose on my own, I'd have someone there anyway to patiently remind me that right=tight, left=loose, because I'm terrible about that at the best of times.

I did manage to get one of the transmission cooler line end fittings off on my own, though. One. And I think that had more to do with it being absolutely shocked at the language I was hurling at it.

As for the *****, I know exactly what you're talking about. It seems all nice and roomy under there and suddenly the thing's all personal and taking liberties.

Since I don't know how to quote multiple posts....

roninofako:

I have a Haynes, the FSM, and the whole internet. And I wouldn't have the FSM if I hadn't learned about it here [and been told by more than one user that I should get one]. I think they take a bit of training I do not have to fully understand, but I'm working my way through that.

tjwalker:

I'd pretty much reached that same conclusion--that, since mine is ODBI, having a second one wouldn't make much sense. I'm willing to search out possible 'downstream' locations anyway, though, on the principle of 'it would be just my luck to get a freak-Jeep'.

If I found a second one, I'm not sure what I'd do. Possibly give up and send the thing off to one of the surviving freak shows.

I went with NTK after checking around a bit and seeing what others had to say about other brands. If this ends up being some sort of ordeal, I don't like the idea of going through it again.

I ordered it from RockAuto this morning, and it was shipped within the hour. Now I just wait, review the information I have, and worry about stupid things like 'wait, that's exhaust, and exhaust is hot. If I spray PB Blaster on it, how likely is it that there will be a fire later?'

Rogue4x4

To multi quote, pick the posts you want to quote by clicking the " button in the bottom right corner, it will change color, more than one post, click the next one and so on, and on the last one hit quote.