Just installed a set of mil sensor eliminators a few days ago and cleared the cel by removing the negative cable from the battery for 10 minutes. I was out last night and the cel popped back on. I ran the p0420 on the Actron and it was "catalyst system efficiency below threshold bank 1". I know this is due to the fact that I have a non catted Flowmaster system in place, but I was hoping the eliminators would solve it. I have read several posts that the mil sensor eliminators are hit and miss. Some guys have luck with them, some don't. Kind of thinking I'm in the not so luck boat here. Any other things I should be on the look out for or just learn to live with clearing the code every once in a while? Thanks! Shameless plug. '96 Cobra, E9 Laser red/saddle/saddle, mint, 29k original miles, no mods except for Saleens and Flowmaters. LOOOOOVE IT!!