I have 02 deville with check engine light on. I went to "oreilly" and hooked it up to diagnostic..the code showed me that it was a secondary air pump. I calle dthe dealership and they said it's a pump that heats up the catylitic converter and assists with emmissions?/ The dealership said they wanted like 800 bucks to replace it? Has anyone dealt with this and if so, was it easy to change yourself??