front o2 sensor --when do you change it?
 

I am trying to do as much preventive care for my car as possible and I have never changed my front o2 sensor. Almost 83K miles on it and it has had a hard life. Including water methanol and many many track days etc.
I recently had a dyno tune done and it seemed to function well at that time and really nothing has changed. But, when I thought about it, other than actual symptoms/codes that it may develope, i know little about when to replace it?
Is there any things to look for on Cobb logs etc that may suggest its time to get a new one? My logs seem to be OK. I also run a LC 1 innovate wide band set up and the readings from it is very simular to the oem one?
After 8 yrs of hard life--would it be prudent to replace it? Or money wasted?

IMO, this falls under "If it ain't broke don't fix it". An O2 sensor either works or it does not. If you are already under there and doing other work and have easy access, sure go for it. They are not that expensive and a little PM never hurt any ones car. If you just want to do it go for it. If it fails however you will get a code for that.

What happens when it fails is that it registers 14.7 as the default AFR and all fuel trims are frozen - plus the code .
You can still drive the car ok but AFRs will wander around a lot - mine went quite lean at cruise.

good info --thanks guys.
it is a little expensive---over $200!

I replaced mine at 35k. The cel comes up :(
Save your money if its still good

I relplaced mine at 60K miles......thought it was a good time :)

I watched a tech episode (can't remember what show) on Speed and they were discussing O2 sensors and specifically new technology and a new O2 sensor that was just released by Denso (or was it Delfi?). Anyway, they had a representative on that stated that O2 sensors die over time and that the accuracy falls off as they age. Now I know it's just a show and could be complete bullshit but I went ahead swapped mine out when I installed the new engine.

thats was what I was wondering about. Is there a decreasing responsiveness that can be seen without an oscilloscope?
Piece of mind comes at a price maybe?

This is true. Over time it will "wear" and will not be as accurate. I was recommended on my last car to be replaced every 100k miles. After replacing it my mpg went from 25mpg to 31. Not a huge improvement, but it paid for itself after a few months.

That being said, the o2 on my last car was only $70 from the dealer, the rx8's cost quite a bit more. I wouldn't change it unless I saw a reason to. (mpg drop, or running issues)

Great, just great.........thanks so much for giving me something else to think about doing in the future! :banghead:

FYI................I think I would go new, but this guy with 40k miles is selling his for $100.00 this morning.

https://www.rx8club.com/rx-8-parts-sale-wanted-44/2005-titanium-grey-rx-8-part-out-227831/

I got mine from a low mileage (22k) 2007 RX-8 :) But if you need a new one contact www.sparkplugs.com

I will go new if something. Like I said before my failed at 35k. I am the first owner so it was original Oem mazda sensor

Another good reason to have an aftermarket wideband if you are FId .

I have found (in almost all cases) aftermarket widebands generally read leaner under load than the stock one does , by as much as one whole point.

This one?
http://news.speedtv.com/article/0cfp0Kd9Lxcws

More often than not because it is located further downstream and is potentially being impacted by a leak. There's a reason the factory one is located in the manifold before the first piping connection. Another potential factor is that most people aren't very good when it comes to wiring in electrical components.

Yeah an aftermarket one is a must.

No, not that one. It was a show. Two guys garage maybe?

Preventive maintenance is a good thing. But, replacing an O2 sensor that is not damage is a waste of money, from my perspective. It only sense whats wrong with the car, not helping the car to start and run normally.

you are probably right--- but after 8 years and 83K hard miles i have a new one on the way.
Mine seems to be functioning ok, but for me its peace of mind i suppose.
When you FI this engine, prevention maintainance is a key longitivity requirement.
Maybe this could be added to the list?

On RON95-97 fuel, accuracy will maintain for about 2000 hours. With premix = lower. After 2000 hours, accuracy will drop a bit and it will fail when time comes.

good to know---thanks.

Smart changing it when you could!
for anyone changing an engine, do yourself a favor and replace the Front 02 sensor. If you have access to it while it’s pulled that will save your a lot of trouble. My engine still had the original from 2006 and they just seize themselves overtime. I’m waiting for a price on a new one from a friend at a dealership I get a small discount on. If anyone has any links to some good deals please share.

....and they just seize themselves overtime.

Kopr-Kote® is your long term friend.