Mazda Repair: oxyegen sensors, o2 sensors, o2 sensor

Question
the check engine light is coming on in my 1999 mazda 626. i had the car checked and my mechanic thinks its the o2 sensors is there anyway i can be sure about this ?can i install them myself ?   thanks tony  

Answer
well how has the car been running? things like fuel consumption, idiling or running rough, things like that? If it is an O2 sensor then I wouldn't recomend you installing it your self unless you have the right amount of experience to do so because if you don't have the experience then you might end up making things worse then what they are right now.