is the remote start with the CEL a GM thing or a special way it is wired? my Ram will still remote start fine with the CEL.
hell sometimes the remote start will throw a mis-fire code as well.
did you happen to fuel up with the engine running? that will throw this code as well.
check the filler neck for corrosion, also check the o-ring on the gasket for a crack, split, or something along those lines to prevent a good seal.
or you could just replace the gas cap and remove the code, if that doesnt work try replacing the purge solenoid.
otherwise if you can find a vacuum leak or see a crack hose or evap canister, the mechanic will have to fill the system with smoke and look for the leak that way.