I had mine P20EE come on a week or so ago and did not notice any issues continuing to drive it. I read it with my code reader, but did not erase it. I couldn't get into the dealer right away, so I went in and erased it because it was bugging me. So... when I did get into the dealer a few days ago to get all my Recalls done, I told them about it and showed them pictures of the CEL and Code readout (on my Reader). But they would not address it, change anything, etc., because I did not bring it in with the CEL on showing that Code. So next time, I'll just leave it on and come in. Or perhaps I'll just get lucky and it was a fluke and it won't come back on. Not a big deal one way or the other, since emissions are covered for quite some time still.