when should 02 sensor be replaced on a 2000 acura rl

I could find no set interval to change the 02 sensor on your Acura, so my answer is when your CEL light comes on and your OBD codes show that it is bad. (I have no way to cross reference to find what code it is) and/or you notice a dramatic drop in gas mileage, engine running too rich (black smoke from exhaust) or too lean, rough idle

Heeeeerrrreee we are, go read: http://engine-codes.com/p0135_acura.html ...and as for your original question..in mileage..it should last a bare minimum of 50,000 miles, and up, maybe WAY up

The sensor should be replaced whenIt goes bad. It's not a preventative maintenance thing.

I've been looking at your answers to several questions mrmooney this morning, going thru my email to responses, and they are all very good, this one included

Thanks coming from a large caliber person such as yourself, it means a lot.

I'm flattered and speak the truth. Thanks

Generally speaking, O2 sensors get "lazy" around 80-100K miles. They still work and don't throw a code but MPG's can be gained if they are replaced. If you shop around on eBay your can find low mileage used O2 sensors on eBay. The one I found was used on a dynomometer. You can test the speed of your O2 sensor if you have a meter and a torch. Search the net for instructions.