My mechanic tells me i need a "smoke" test to determine why the scanner several times gives an Evap leak resul?

how does a smoke test work and does it check the muffler (catalytic converter). i've had two Evap valves changed different ones (2 types). and the check engine soon light still goes on after i drive hard. it's an 03 Altima.My mechanic tells me i need a %26quot;smoke%26quot; test to determine why the scanner several times gives an Evap leak resul?Basically he is going to hook up a machine that puts %26quot;smoke%26quot; into your EVAP system. This is basically the system connected to your gas tank for emission reasons. This %26quot;smoke%26quot; will come out where you have a leak causing your check engine light to come on.



So basically, it does NOT check your exhaust system (catalytic converter or muffler).