Poor Gas Mileage and Rich Exhaust Smell

[So Cal Mark]

the gas sensor light is on a speedo counter; it comes on at a designated mileage and has no connection to how the car is running. If the car indeed is that rich, I'd get it diagnosed soon. An overly rich mixture will ruin the catalytic converter, can result in increased engine wear by washing oil off cyl walls and diluting oil. If the pressure regulator is not leaking, you could have a cold start inj leaking or staying on, a temp sensor out of range or an afm that is misadjusted or defective

[rlux4]

The exhaust gas light comes on roughly every 30,000 miles as a reminder to change out the O2 sensor. So it's not being set off by emissions. It needs to be reset to get it to go off. The reset switch is under the driver's side dash, to the right of the steering column in a black box. If I remember correctly, you remove the screw that has a knurled nut on it and push in with something small (I use a small size allen wrench) until you hear or feel a click. It should be reset then and the light won't be on constantly.
Ron