cel on on 1999 Toyota Camry

my cel lite has been on steady for past 60k miles local Toyota dealer suggested change fuel cap, which I did, still on, can disconnect batty and lite goes off, but reappears after 30 miles of driving, any suggestions

1 answer
Your car has on board diagnostics 2 (OBD2). Did the dealer plug in a scan tool to a 16 pin diagnostic socket under the drivers side of the dash to retrieve codes stored in your cars computer.
If they guessed it was a gas cap issue the light was turned on when the computer saw a fault with the evaporative emission system and the system needs to be properly diagnosed not just turn if the light. If it resets the Check engine light a second time there is a problem and a Toyota dealer or Toyota specialist/independent repair shop should be able to fix the problem.