My MY00 is eating up O2 sensors? I have a 2000 2.5 RS. I modified the airbox filter and I changed the Muffler( very low restriction). I have reset the computer by disconnecting the battery for the half an hour and stared the car cod and let heat up not touching the throttle. And lately I have been doing a lot of Highway miles (by the way I have 39000 miles) and I am get a lot of backfire in the muffler and exhaust, I like it but I need it to stop, when i let of the gas pedal, around 2nd, 3rd gear. Is there a computer link I can get? Snap-on tool anything?

Backfire is very common when you upgrade your exhaust. Heck even when i had stock exhaust I could hear it. Our cars run rich in stock form so you can hear the gas hitting the exhaust manifold. I wouldnt worry about it, if it irrates you get a resonator put on to tone it down.

Buster

What about the o2 sensors? Why would I be going thought them?

Did you install the O2 sensors yourself?

It's very hard to keep our cars from backfiring. When you add low restriction exhaust to our cars the exhaust gas velocity dies and more unburnt fuel collects in the pipes. Upon the application of more throttle, that fuel ignites and POP!

The dealership installed one O2 sensor at 35950 miles, then the light came on agian, took it back and they said that the sensor worked and they flashed the ECM, then not even a day the light came on agian. I was going to take it back right away, but reset the ECM myself with the battery. Then just last week Wednesday, I took it back to the dealership and the said that the O2 sensor needed to be replaced, they replaced (2nd one) it agian the tech said it was cause of my modified airbox and exhaust system. So no I never changed myself. I need to know weather there is a tool to read the computer, instead of going to the dealer, HELP ME

Very important...make sure the first 02 sensor is close to stock location...if farther downstream will have delayed reaction to swift throttle movement,causing backfiring.
Jeremy

If all you have is a different muffler they are full of it. Subaru sells a low restriction intermediate pipe AND muffler for our cars. Don't let them pitch that crap.

Do you have the recalled O2 sensor. It is common to go through O2 sensors with a MY00. I have been through like four or five or something. They recalled them last year maybe, which seemed to work for everyone else, but I think I am the only one I know of to blow the recalled one. If the O2 sensor blows, just resetting the ECU won't fix anything. It will just make the CEL turn off for a day or two. I think that there is a CEL mod for the O2 sensor, if you are throwing the 420 code, you could try that if the dealership doesn't replace your sensor for free.

-Wes