Check Engine Light

>They are about $25 a piece if you buy them generic instead of
>from the dealer

Over 15 years, we have replaced the O2 sensor 3 times. Each replacement has
been the generic. Mazda wants over $200 for them (ACK!). Although the generic
seems to last only a few years, it's worth it. The symptoms of bad O2 sensor
always before was poor performance, slight stumbling, etc. This time, the car
ran like a top........but with Check Engine light on. Took us awhile to get
around to testing the sensor as it didn't occur to us this could be the
problem....

Geeze, ya never know. To know how to test, check a Miata shop manual. Gives
details on how to do it. You will need a volt meter.
~Cissy :-)