I haven't had a chance to take my TCH to the dealer yet since the check light came on (I'm driving my wife's car). However, remembering that I filled up the gas tank only 3 or 4 days ago (isn't it nice how long we go between refueling!), I checked the gas cap. It was on - but not tight. Note that the "filler door open" light on the MFD wasn't on, since the filler door was closed and the cap on, just not tight. I must not have screwed it on tight enough, and it loosened to the point that it clearly wasn't sealed. I'm guessing this would trigger some sensor, since as I understand it the tank does have some sort of leak test. I've tightened the cap, but the check light is still on (though I haven't driven anywhere yet). Any thoughts? I guess even if I fixed the problem the dealer still needs to reset the check light. Obviously, I should get a scangauge II!