1999 camry malfunction light on

Hi guys, my dashboard malfunction light came on the other day. I took it to my mechanic who thought that I probably forgot to screw the gas cap on tightly. He did a diagnostic test and came up with the code P0446. He resetted the light. I drove for a day and then it came back on. Has anyone had any success in determining what the problem is. I’ve read that it could be the gas cap, charcoal canister or vacuum hose? Any guidance to where to start.

I am going to guess that code is related to the vapor recovery system.

You could have a bad gas cap (it happens) a bad sensor or something bad with that system. Do you tend to top off the gas when you fill it up? If so you may be the cause of damage that it is now reporting.

Here is what the code stands for:
Evaporative Emission System Vent Control Circuit

This is saying there is a circuit problem so you need to check the circuit going to the vent control. Check for a open circuit that may be due to a bad connection. The circuit could be shorted also.