car running rich

just change the oil & filter today in my 85 lesabre.. had a slight smell of gas to it. also when letting it idle in the driveway there is a noticeable gas smell. once when i pulled the codes from the onboard computer it was complaining about the oxygen sensor.. could this be causing it to run rich and smell like gas everywhere? thanks

check the o2 sensor. if its running rich it could be because of a bad 02 giving a slow or no reading. how is the gas mileage on the vechile, if its using more gas than usual i would change the 02.