i keep taking my car to the dealer to get my 02 sensor fixed but like 2 weeks later the check engine light won't come on! the car doesnt run differently but its annoying as hell to have that little light on....any suggestions?

 

Check for resistance on the O2 line. Is this car new? or recently bought?

 

i bought it 8 months ago and have had ongoing trouble with this damn thing. i bought it used....its a 00' LS.