Whats a 0442 Code

Today my 2000 k1500 5.3 thru a 0442 code which is "Evaporative Emission Control System Leak Detected(small leak)". I have no idea what that is...can anyone give me some direction?
Thanks,
Sonny

That means that during a normal engine run cycle, the fuel tank was not able to maintain a light vacuum (usually 1" Hg) for at least 20 seconds.

That can happen if the fuel tank has vapor leaks, the PWM vacuum control solenoid for the fuel tank is failing or has lost its engine vacuum source, or the evaporative emission control charcoal canister has a leak in the vapor or purge system.

It also happens very frequently when the fuel tank is filled while the engine is running or the fuel cap is not installed tightly or is leaking air. Any of those will constitute a leak into the tank, and therefore the tank pressure control will not be able to achieve a slight vacuum in the tank and system. The DTC is set when the system can hold some vacuum, but not correct vacuum.

Thank you very much!

I bought a locking gas cap when gas prices went sky high so I went back to the stock cap, cleared the code and so far the SES light has stayed out!