there are two on mine, only the front though? even if BOTH are original from 215k miles ago??

 

Well, if the ECU isn't complaining about the rear one, then save yourself $90 and leave it where it is.

The rear one has no effect on how the engine runs... It's only there as a comparison point to check how well the cat is working. If/when it finally fails, then the ECU will think that the cat has problems.

 

anybody know where to get an inexpensive o2 sensor for a 99 tacoma v6? Is it the same as the one above? Thanks.

 

What's "inexpensive" to you? They're pricey in general.

URD will beat the dealer...
http://www.urdusa.com/product_info.p...s_id=430006000

Find your year & engine on the list - pay attention to if you're a CA emissions truck.


DO NOT USE A GENERIC SENSOR. It won't work and/or it won't last.

 

well technically the ecu isn't complaining about anything, i was just told that if I replace them (since they are so old) i'd improve mileage.

i guess it makes no sense then to replace the rear. but should I replace the front after so many miles even if i'm not getting trouble codes?

 

I figure we're talking about your '90, right? I'm not sure of how close your ECU watches the sensor, so it's hard to say. e.g., in the OBDII world ('96 and up) the ECU can post a wide variety of trouble codes against the front O2 sensor: Range too high, too low, slow response, no response.... I know the ECU in your truck will trip the CEL on no response, I don't know if it's looking for some of the finer points.

What I'm getting at is that "Given that we're talking about 16 years and 215,000 miles, it can't _hurt_", but it may not change anything either.