How to diagnose an EVAP leak with a smoke machine

EVAP leaks are where a shop can waste a lot of time if the first move is throwing a gas cap at every P0442 or P0456. I still check the cap and filler neck, but I do not sell a cap unless the test points there. A smoke machine makes the job cleaner if you use it at the right pressure and seal the system the right way. I start with the scan tool. I look at the code, freeze frame, fuel level, purge…