how do you tell if your o2 sensor is working? and what effects does this have on your truck if its not?

 

it defualts to a factory program which will cause the truck to run rich and burns more fuel

 

Thats the problem ive been having is horrible gas mileage its just seems to keep getting worse.i know i have a tranny slip in od and a exhaust leak but even with both of those i was getting around 12 mpg but here recently ive been getting about 8-9