Last week the space where the odometer, MPG meter, etc. sit suddenly spat out "CHECK FUEL CAP" for the 1st time. I was surprised, since I always tighten the cap after refueling as per the manual (and a loose cap is supposed to trigger the "check engine" light, which never came on). Besides, the previous fillup was 4 days earlier. So I unscrewed & rescrewed the cap -- no help. Then I wiped the cap & filler neck down with a clean rag -- also no help. Called the dealer's service dept. and reported the problem; they said to bring it in as they were the ones who had to reset the sensor. According to the service guy, a large ambient temperature fall can cause this (and we did have a strong cold front drop lows from the 60s to the upper 40s). Still, this had never happened on either of our HCH2s before, and we've had them for 20 and 12 months.

Has anyone else experienced this warning?

 

Yes, this is fairly common. Next time, just unscrew the cap and rescrew it like you did, get four or five clicks out of the cap, and go on your way. The warning will clear itself after ten or so engine starts.

 

For the time being you can hold down the reset button. That will temporarily clear the message so you can see your temp, mpg, etc. Also do a search for this in this forum. There are a few other threads about this.