....for anyone that has changed out the O2 sensors FWD of the CATs voluntarily (i.e. without any codes or symptoms of it being needed):

1. Did it provide a lasting boost in engine performance?
2. Did it have any ill effects on your catalytic converters?

I have read that it's not a bad idea to do this preemptively, but I'm balancing that with an "if it ain't broke" mentality, and I'm on the fence.

Thoughts?

Thanks,
Houm

 

Bad idea to do prematurely? I have never heard of that and there would never be any bad side-effect to doing so. Its a sensor after all. Typically they are done at a milage since by the time codes come up you are already trashing the cats. It used to be 60,000 mile interval, then 80,000. With most modern engine and I believe the LR3 100,000 miles it the interval.

Performance is typically a little better since new O2 sensors will respond a little quicker. So typically a nice boost but not like having a tune done sorta boost. Economy usually goes up too of course as I did, but I dont think it was a lot. 1-2 mpg maybe on the highway. My best is 22mpg on a trip, 20 is pretty easy. 18 if I am getting aggressive. In town only I get about 15.5-16.5mpg.

 

...I'm at 129k and they have not been done. Would doing them help preserve the cats???

Just trying to see if I should change them for the hell of it or just wait until the cats need out, then do all of them.

 

If I were you, I would do them. 129k is well past prime. I did mine at 110k, I think. I was not sure if they were done before since I bought it at 105k. If you buy the Walker brand O2 they are Denso repackaged. So you can save some $$. I am running them now. Downstream sensors last a very, very long time since they get to live in the "clean" air. I have never replaced a downstream sensor out of need, meaning I have never in any vehicle had a code from one. Which is good cause a code from the downstream means the cat may be shot.

As for waiting, you may end up risking the cats. I mean the LR3 is pretty "modern" though so I would think you would have other issues before they really go. But I then I think about all the LR3 with cats that people claimed needing replacement. So if the LR3 cats are a bit sensitive I would say all the more reason to replace the sensors at regular intervals. I mean 100k miles between a parts change is pretty darn long. Frankly you may do these only once with that vehicle. Price for a set is less than $200 - much cheaper than cat replacement I would think.

 

And I will add that the passenger side is a breeze. Driver side is hell. You probably know all that. But one thing that was never mentioned in anything I read was a top down procedure for driver side. Only after I got frustrated did I notice it may be possible to remove/install the new from above. You would need some extensions, swivels, etc. But at the very least you can get your arm down to get it threaded. So if you do from above, let us know it can really work for sure. I was already well into tightening it down before I realized. From below I just had no room, even with the front shaft out of the way. Also there is some access through the wheel well even with the liner in place. So another area to look that may help, probably more for removal though.

 

....about $540+ tax.

I appreciate the insight. It's a datapoint. I don't want the new sensors to send my old cats into a tizzy....and if the new sensors don't yield a performance benefit (or extend the life of the old cats) them I would wait.

 

I think Denso is OEM for LR on the sensors. LR does not make em. Just like the MAF - which is even pointed out in the LR tech training. $540 for a couple O2 sensors though, ouch. Guess they really needed funding for the new Defender!

 

HI please suggest or post a link where I can get the upstream and downstream Sensors that are OEM for the better price.I was going to get them from Atlantic British but have been putting it off since the guy who used to advise us is no longer on the phones.We have 216K miles and don't remember ever changing those and only get 12.6 mph compared to 15 which we used to get back then.thank you

 

Feel free to contact Eric Riston at x231. He's our longest-serving parts rep, is very knowledgeable, and would be glad to help you with your O2 sensor needs.

 

Thank you I just received them from Chip..
nice guy I appreciate it.