P0440 Evaporative Emission Control System Malfunction is fairly broad. Unfortunately, there are a number of possible culprits that could cause this code to be set, hence the technician\'s seemingly broad range of possible trouble spots.
Having a \"smoke\" check is not a bad idea - this sort of test can quickly pinpoint any leaks in the system and can eliminate possible culprits. As the extent of the EVAP system runs from the gas fill cap all the way to the throttle body.
The I/M readiness monitors not being set after 80-100 is also possible, as it goes on a preset number of starts/stops, engine RPMs, temperature ranges, and engine loads. Sometimes it will be set as soon as 50 miles, sometimes it can take as long as 200-250 miles. All depends on the driving conditions.
As Dave indicated, the most common cause is a loose or faulty gas cap. Sometimes that rubber gasket on the cap will not seal against the neck of the fill tube, no matter how many times you get the cap to \"click\". The gas cap can be pressure tested separately, this will also be checked when they do a smoke test.
Topping off the gas tank can also cause this code to pop up. If you get into a habit of topping the tank off or rounding it off to the nearest dollar amount, I would highly recommend to stop that practice. Reason being, topping off the tank can flood the vapor canister with raw fuel (fuel will be forced down the vent tube into the vapor canister). Once this canister is contaminated with raw fuel, it will be damaged and will through this code.