O2 Sensors?

[Zchild]

I'm currently contemplating preventative maintenance on my O2 Sensors. I'm only going to do the pre-cat's at this upcoming DIY, followed by the post-cat's at the next event. I'm just trying to figure out if its best to change out the pre-cat's or the post-cat's for the best bang for the buck. I'm having no trouble from either pre or post cat's at this time. I'm just nearing 277,000 and the O2 sensors are next on my list of tasks to complete prior to 300,000 miles. Thanks for your input. Happy Motoring...

[1996 328ti]

I wouldn't change something that works, even as a precaution.
It sounds like you have some lucky 02 sensors. They normally don't last that long. I'd stick with them. Change your brake fluid instead.

[Scotty]

I wouldn't change something that works, even as a precaution.

[1996 328ti]

I just don't believe in changing perfectly working parts. Why fix it if it ain't broken?
I don't think there will be any change in performance with new sensors.

Now brake fluid, you can feel right away.

[Zchild]

I understand what you're saying Steven, however I just changed the brake fluid when I changed the brake pads and rotors two months ago. I've changed nearly every part on this vehicle except the O2 sensors. I got a CEL during the last tour in the mountains and it mentioned my O2 sensors but I believe that was due too the higher altitude of the Blue Ridge range. Thanks for the input, but I believe I'm going to opt to change the pre-cat O2 sensors at the 13 Dec DIY, followed by the post-cat O2 sensors durung the Jan DIY session.

[1996 328ti]

I got a CEL during the last tour in the mountains and it mentioned my O2 sensors but I believe that was due too the higher altitude of the Blue Ridge range.

Then that is different. Your sensors are probably right at borderline. I had a CEL due to an 02 sensor. Nothing that a few minutes of WOT couldn't take care of.
I don't think altitude had anything to do with it though. I've driven in and around Keystone, CO and I think it's a tad bit higher that anything you will find on the Blue Ridge Parkway.

[Scotty]

I just don't believe in changing perfectly working parts. Why fix it if it ain't broken?
I don't think there will be any change in performance with new sensors.

If you've ever looked at the output signal of an old O2 sensor, you'll see that it is indeed degraded. The sensor is working, but not "perfectly working". Hence, the DME will occasionally receive incorrect lambda values.

When it's time, it's time. Same goes for spark plugs and any other electrical part exposed to harsh conditions. It makes no sense to put it off.