O2 Sensors?

[jordan325]

After reading through the boards, I was wanting to know why the Galants have such a problem with these? Does anyone know if this is an expensive repair? I currently do have one that is bad!
And what is the actual function of this sensor?

[pinoyesv6]

the reason our cars are so sensitive when it comes to o2 sensors is because they are maily used for emissions controls. on a cali spec galant (the ones most of us have) there are multiple oxygen sensors. you mess with some of the emissions control devices like the cats, and the oxygen sensors more than likely will pick up that you did. it monitors it to make sure its still working properly.

[PaulBlackGSX]

The front oxygen sensor(s) is used by the ECU to monitor how rich/lean the car is running at part throttle driving (ECU ignores the o2 sensor at WOT). The car adjusts the fuel trims to try to help ensure the the ECU is delivering the correct amount of fuel. If your front sensor goes lazy or fails, you will want to replace this since it can certainly cause at the very least, poor gas mileage.

The secondary or rear o2 sensor(s) is purely an emission control device. You wouldn't effect anything on the car if you put a 25 dollar O2 simulator in it's place (though technicall that illegal :wink: ).