Same thing just happened on my '09 RX350. Took it into the dealer and they charged $110 to reset the computer. Their explanation was that apparantly the gas cap had not been turned tight enough and that this triggers the "check engine" lite because of lack of pressure in the gas tank. This then reduces the power to the Trac system which reduces its ability to perform properly (or something along that line of explanation).
I'm not sure that just resetting the computer is the answer or how this is done, but $110 wasn't to big a price to pay for the peace of mind that it was handled properly. I was 2,000 miles from home and had to drive through the mountains to get home. The Trac system would have been useful if I hit some bad weather.
Good luck...
