Hi, I have a Picasso 2002 model, doing this from day one. Dealer also said to ignore this. I noticed that the light would come on shortly after I refilled the tank, only once I drive the tank empty, and have it refilled (at another pumpstation) it would go away after a few km. It made me to come to the conclusion that some storage tanks at filling stations are not clean - I now stick to 'clean" big stations - how you are going to identify that is trail and error. The car now have 204000 km on the clock and this behaveour is "consistant" with my theory. I use the SAME 2 or 3 stations in the area I normally move (work & live) in, NO LIGHT, but when going on holiday - that is usually where it starts lightning up again, If I go a route I had done before, I now "know" which stations tanks are "clean" and only use them, once I hit a new route, I am in for the "lightning-up" senario again - I would say, dont be TO bothered about it - one dealership wanted me to change the oxygen sensors at a HEFTY price, - lucly I did not - censors tested FINE, and I'm still going happly!
BUT get it checked by a dealer - I insisted to stand NEXT to the tech whne he hooked the computer up - NO abnormal readings were refelcted by the sensors..
Regards
Vivaldi, June 2009