Could a cold air intake throw off fuel trims ? I put a cold air intake on and she popped a engine light with P0455 code for mass evap leak Mechanic told me that cold air intake could have caused it, just wanting another opinion

 

I am going to say very doubtful. A small evap leak is an emissions issue, NOT an air intake issue. This could be as simple as a loose gas cap.... Or more advanced such as a problem with a purge valve or solenoid or a leaking vapor line or hole in the gas tank or filler neck. But not a cold air intake.

Now how does fuel trims and your evap leak code relate? Do you monitor your fuel trims and notice a change after installing the intake?