I keep getting code p0441 which is evap emission control. took it to my mechanic said it was the gas cap being loose. but it came back on and i know i tightened the gas cap enough. what else could it be?

 

P0441 is the Evaporative purge regulator valve. it sites just behind the air filter box and has several hoses and electrical connections.

Check the hoses coming in and out of the evap valve, especially the little grey and white one way valve on the vacuum line right behind the air filter. This sometimes rubs against some metal clips and wears a hole in itself.

The Evap valve sometimes gets stuck due to charcoal dust, Give it a few gentle taps with a screw driver.