I stopped at the side of the road and checked the cap by removing it and putting it back on. The message did not go away. I restarted it a number of times hoping to clear the error but that didn't work either.
First hiccup? The thing is I'm usually pretty careful about tightening the cap and making it click several times. I do admit on the last fill up, I thought the leash for the cap was twisted a bit strangely around the cap. I didn't bother to re-do it at the time.
After checking the 2006 Honda Odyssey owner's manual, this is what it says on page 82 about the Tighten Fuel Cap message:
The TIGHTEN FUEL CAP messageSo I guess I'll need to drive it a few more times and see what happens.
should go off after tightening the
fuel cap, turning the ignition switch
off and on, then driving over 30 mph
(48 km/h) for at least 45 seconds.
Due to different driving conditions, it
may take a few driving trips to make
the message go off.
If a loose or missing fuel cap was not
the cause of the TIGHTEN FUEL
CAP message coming on, the
message will turn off and the
malfunction indicator lamp will
come on. If this happens, have your
vehicle checked by your dealer as
soon as possible.
UPDATE: 6 November 2006 - 1381 km