so I have a 96 bonne se and it is getting like 13 mpg and the car sounds and feels like it is running great. So i have bosch spark plugs with ngk wires and they look ok. i dont know how to check if my o2 sensor is bad but it looks ok as well. Has anyone ever had this problem or have any suggestions???

Changing the O2 sensor would be a good idea. You can find a good one as www.rockauto.com Just don't go with a Bosch O2 sensor. They don't lost long. I have a write up on how to change a O2 sensor, should be in the how to area. If it'* not there I'll add it.

could it be possible my car still be running good and idleing good if my o2 sensor is bad? and would it make my gas mileage that bad???

RockAuto Parts Catalog which of these o2 sensors should i get???

Yes, a ban O2 sensor will drop your milage. When I got mine I got a Denso, desco, I can't remember right now. I'll have to look that up when I get home. Just not a Bosch. And you want a front sensor.

I would even lose the 'Bosch' spark plugs as well if I where you. Bosch and Bonneville don't mix well.

DENSO Part # 2344012
Front
$32.79$0.00$32.79

ok thanks guys i am going to give this a try.

ok i havent gotten the o2 sensor yet but now the car will sound like its going to die when im at a light. the voltage on my battery gage goes way down until i start driving again, what could this problem be? maybe o2 sensor, maybe fuel filter?? any help would be great.

Have you checked the car for vac leaks? Also check the spark plugs to make sure they are not fowling. Check all spark plug wires to make sure none are damaged or grounding out. Check to make sure none of the spark plug wires is near or touching the O2 sensor wire, #4 and #6 are good for this. Lets see what we find and go from there.