o2 simulator

Anybody ever hear of these?http://www.highrevmotorsports.com/catalog/default.php?cPath=80_330

i just saw one of those on ebay. my check engine light is on too and its because of the o2 sensor. i was going to buy one and replace the old one thinking i have a bad sensor.....now i wonder if i need one at all.

is this a common problem with bigger exhausts?