100k miles on original O2 sensors?

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Jan 16, 2006
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Just turned 100k & it has never lit the "Check Engine" light. Should I continue driving it as-is with the old O2 sensors & wait for the eventual fault code? I'm not used to being able to go this far on original O2 sensors.
 
I would just drive it till the O2 sensors go bad. It's not like it will leave you stranded the day they do go bad. However, others have reported better mileage after swapping O2 sensors, even though no fault codes showed.
 
Donco,

Got the check engine light at 89,000 miles. Replaced the front and rear bank 2 sensors. $125 parts cost for each bank. I'm not sure what the down side is of waiting until you get the fault code. When I asked my mechanic if I should repace all the sensors he said wait until they go out.

Hope that helps.
 
O2 sensors . . .

The fronts are the only ones that feed the ECU for closed-loop fuel injector feedback. The only purpose of the rear ones is to verify the cat's are still in good condition. Definitely wait until it throws a fault code before replacing the rears. Improved gas mileage with new fronts is incentive to spend the money before waiting for a fault.

No tape over the CEL, it lights up with the key in and goes out right away when started.
 
three weeks ago... 48.5K miles and she threw a CEL. bad O2 sensor.
 
Last edited:
'99 LX, 90k miles, getting 17+ mpg on recent tankfull. (Was getting 16 before new plugs & recent oil & filter change...)

I guess my O2 sensors must be OK?

I wonder if replacing them would gain me even 1 full mpg? Dunno if the beast can possibly get 18 mpg.

(EPA rating on window sticker is 13-16.)

But fuel economy is devilishly elusive to pin down. Affected by lots of things, including the driver. Without a rigorously controlled test, a slight gain can't be verified or quantified, apples-to-apples.

Anybody care to offer their estimated fuel economy improvement gained by replacing 02 Sensor(s) that were not yet failed?
 
I'm throwing PO155, bank 2 sensor 1. Will replace bank 2 sensor 1 and sensor 2 in the next couple of days. I bought a front and rear so I might as well replace them both.
 
For those who never venture into the 80 series forum, there is an on going thread on O2 sensors. I still say don't fix it till it's broke. I'm on 97k miles with the original sensors. I have had O2 sensors go out on other vehicles between 60k and 150k--quite a spread. I would say servicing your fuel injectors at 90-100k would give a more probable performance benefit.

https://forum.ih8mud.com/showthread.php?t=75975
 
hoser said:
For those who never venture into the 80 series forum, there is an on going thread on O2 sensors. I still say don't fix it till it's broke. I'm on 97k miles with the original sensors. I have had O2 sensors go out on other vehicles between 60k and 150k--quite a spread. I would say servicing your fuel injectors at 90-100k would give a more probable performance benefit.

https://forum.ih8mud.com/showthread.php?t=75975

I had 135K+ miles on my 1995 FZJ80 and no problems with the O2 sensors, I will wait for a problem before I change the O2 sensors. Just a cost benefit approach.
 
My DS front O2 sensor gave me a CEL at 96k milles a few months ago. I replaced it and 2 months later at 98k miles I got a CEL for the PS sensor and replaced it. I personally would not replace sensors until they are asked for. The post cat sensors are even easier to get to but one should get new nuts as these are bolt on w/ a gasket. The fronts just screw in.

-Mark
 
I just replaced the passenger side front (bank 2 sensor 1) O2 sensor. It was super easy to get to by removing the skid plate and plastic under cover and crawling under the truck.
 
Another vote for "if its not broke don't screw with it".
 
I just replaced bank 2 sensor 1 and the fault code hasn't come back. Is the general consensus to wait for bank 2 sensor 2 fail and throw a code? That's what is sounds like.
 
I believe the general consensus is to wait till it throws a code before changing it, unless someone knows a good reason to replace them in pairs. I ended up just changing the one I needed to.
 
2000 LC just turned 100K this morning, never thrown a code, original O2 sensors and original spark plugs(will replace this year)

1999 LX, original O2 sensors, no codes, new plugs
 
Landpimp said:
2000 LC just turned 100K this morning, never thrown a code, original O2 sensors and original spark plugs(will replace this year)

1999 LX, original O2 sensors, no codes, new plugs

Damn, you only have 400-500K miles left before you might need to overhaul that bad boy :)
 
Isn't the o2 sensor covered under the 80K mile emissions warranty? So if you throw a o2 code and you are under 80K miles just head to the dealer for free replacement.
 
If it fails and doesn't leave you stranded and doesn't do any damage to the vehicle, it can wait.

Does anyone know if the O2 sensors would be covered by the CPO warranty, or is it considered a "wear and tear" item like brake shoes? In CA isn't there some kind of emissions warranty that might cover it?
 

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