my 90 hatch has been getting about 200 miles on a full tank. i did some research and i read it could be my o2 sensor. i dont even remember the last time it has been changed. haha. so my question is, how do you kno when to change the o2 sensor? and how often? thanks!

 

it will throw a check engine light.your best bet is a major tune up.

 

i just changed mines. if your car is equip with a ac, i found it easier to go from the bottom of the car to take off the o2 sensor.my car check engine light came on everytime i drove the car for about 10 minute on the street.cant say it was the o2 sensor or not because i changed the fuel relay and o2 sensor at the same time,now nomore check light