2004 Taurus gets a P0455 code with Check Engine light. Periodially also get a gas cap light. I have replaced gas cap twice and checked filler neck for leaks. Any ideas on where the "ECS Gross Leak" could be?
Could be anywhere along the frame up to the front and back to the gas tank. If you don't find a hose clamp rusted off the hose to the charcoal canister, the best tool to use is a smoke machine to inject white smoke at 2 psi and watch where it seeps out.