o2 sensor

(mercury grand marqui) would like to know what o2 sensor is connected to and where connection is located i loose gas milage when the weather is cold (about 9 miles to the gal) and when it is warm i get about 22.

i think that if your gas mileage dropped that much when the weather is cold you either had a gas leak, or you were blowing alot of black smoke out the tailpipe & fouling plugs, or someone stole gas out of your tank. re-check your gas mileage when its cold. your o2 sensor connects to the ecm and would'nt cause that much of a change in gas mileage if any at all