When to replace the O2 sensor? - JeepForum.com
 
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post #1 of 14 Old 11-22-2007, 09:24 PM Thread Starter
Sakislayer
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When to replace the O2 sensor?

Guys I have a 98 TJ with 112K+ on it and it runs fine. However, it seem my gas mileage has really started to go into the crapper.... I was wondering if might be partly caused by the O2 sensor?

When should they be replaced? My jeep runs great and doesn't have any check engine lights or codes.... The O2 is the original....

Thanks in advance! OH - and is this a self project? or take it to the shop? I know it just screws out, but given my jeep is 10 years old I'm sure it's in there nice and tight....(ugh)


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post #2 of 14 Old 11-22-2007, 11:26 PM
97tjtom
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change em. its a do it yourself job with some PB blaster every day a few days before

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post #3 of 14 Old 11-23-2007, 12:03 AM
MusicMaverick
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Hey, I'm actually over in North Hollywood. Personally, I'd let it go. When the o2 sensor goes bad, the check engine light will come on. That's what happened with mine when I first bought it. It would come on and off, it failed the smog test because it was giving out faulty readings. As long as you're passing the smog tests and the check engine light is on, your O2 sensor should be fine.

When it DOES go, its a very simple procedure. Since it's a southern car, there shouldn't be much rust, worst case, spray a little WD-40 on it. But mine is a 97' with 70k and it took me all of 15 minutes to unscrew it and replace it.

As for your gas mileage, make sure you use Chevron, Shell, Mobil, etc. Stay away from Amco or those cheap ones, they have a lot of additives in the gas that leave deposits. I had the it professionally burned off of the heads and intake. You can try other things like changing the air filter, spraying out the throttle body, and maybe a bottle of injector cleaner, (I've heard good things about the Lucas Tune-up in a bottle)

Other things, if the wheels aren't balanced, that will cause a decrease in mileage. Same with the oil, if it gets sludgy, it will slow things down.

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post #4 of 14 Old 11-23-2007, 02:25 AM
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When you get an extra $70...lol...

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post #5 of 14 Old 11-23-2007, 06:09 AM
Davejb
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Quote:
Originally Posted by Sakislayer
Guys I have a 98 TJ with 112K+ on it and it runs fine. However, it seem my gas mileage has really started to go into the crapper.... I was wondering if might be partly caused by the O2 sensor?

When should they be replaced? My jeep runs great and doesn't have any check engine lights or codes.... The O2 is the original....

Thanks in advance! OH - and is this a self project? or take it to the shop? I know it just screws out, but given my jeep is 10 years old I'm sure it's in there nice and tight....(ugh)
o2 sensors are not maintenance items, when they go bad the MIL (check engine light) will come on.

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post #6 of 14 Old 11-23-2007, 12:00 PM
TMJeep
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They will not always give you a code saying it is bad. Mine started going bad and it would spit and sputter when I would first start to drive it and about backfire. I replaced it after trying different gas and things like that and has run perfect since. I even took it to get the codes checked and it never had any.

You can buy them from www.oxygensensors.com . They were the cheapest I found and get the OE fit not the universal fit.

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post #7 of 14 Old 11-23-2007, 12:23 PM
HipCheck_1
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Quote:
Originally Posted by TMJeep
They will not always give you a code saying it is bad.
x2. I would change the o2 sensor around 80,000-100,000 miles.
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post #8 of 14 Old 11-23-2007, 01:19 PM
redvett94
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Its recommended to change the O2's at 100000mi because they will get lazy and not toggle quickly. The SES light will only go on if post O2 indicated poor cat. performance or the pre O2 completely dies. You just need to replace the pre O2's for economy & performance. The post O2's only monitor the cat. performance.

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post #9 of 14 Old 11-23-2007, 01:53 PM
fish4life
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Quote:
Originally Posted by TMJeep
They will not always give you a code saying it is bad. Mine started going bad and it would spit and sputter when I would first start to drive it and about backfire. I replaced it after trying different gas and things like that and has run perfect since. I even took it to get the codes checked and it never had any.

You can buy them from www.oxygensensors.com . They were the cheapest I found and get the OE fit not the universal fit.
Thanks for that link. My O2 sensor has recently gone bad and i DID get a Check Engine light! The engine light went away after a few days, but even now when i scan the codes it still shows up as "upstream oxygen sensor" even with no light.

I was just about to buy a new sensor here, and they want around $100 in Canada for them. Given the strength of the canadian dollar now, That oxygensensor.com site comes to half price of the local shops. Needless to say, i'll be ordering from those guys

btw, my jeep only has 75,000 miles on it, and the thing went
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post #10 of 14 Old 11-23-2007, 01:54 PM
Wheelin98TJ
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redvett94 is right on.

Around 100k miles they're to the age where they start to get sluggish. The sensor will still perform within the parameters of the OBD II system and a check engine light will not be set off.

Replacing the upstream sensor(s) can improve your mileage. If you still have the original sensor, there's a real good chance that it will.
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post #11 of 14 Old 11-23-2007, 03:20 PM
Rocky.ca
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i didnt get any sort of CEL when my 02 sensors kicked the bucket. I picked both the up / down stream sensors at autozone and noticed a considerable increase in gas milage and a complete removal of the "sputtering" that all 4cyl 97 tjs get. its only like $130 for both, just change em out.

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post #12 of 14 Old 11-23-2007, 04:29 PM
fish4life
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lol ... yeah ... only like 130 ...
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post #13 of 14 Old 11-23-2007, 05:58 PM
Rocky.ca
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oh yeah lol... i forgot, the us dollar took a DIVE. i bought mine w/ my Canadian currency and it seemed like a huge deal to me (i saved about 80 bucks). :P

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post #14 of 14 Old 11-24-2007, 05:55 AM
Davejb
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Quote:
Originally Posted by Rocky.ca
i didnt get any sort of CEL when my 02 sensors kicked the bucket. I picked both the up / down stream sensors at autozone and noticed a considerable increase in gas milage and a complete removal of the "sputtering" that all 4cyl 97 tjs get. its only like $130 for both, just change em out.
I should have said you will usually get a MIL, my bad. Most of the time they cause something to go out of whack that the computer will pick up, but it may not specifically point to the sensor.

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