That was a scary experience. The Check Engine light came on in my 98 SE, so I hopped over to the dealer for a checkup. Turns out that 3, count 'em, THREE emissions' controls kicked the dust and needed replacement. That included the O2 sensor, and I can't remember the other 2. I can't imagine how much these would cost if I was out of warranty. To make it even scarier, that said warranty is up in 2 months!

PS: The car has been babied, they sent me a notice in the mail saying the car is due for 66000km inspection. LOL, the car is still >40k.