It'd really help to know what type of vehicle you have, It's likely a leaking evap line to the purge solenoid or a bad purge solenoid, that's all the help I can give you without knowing what year and model the vehicle is.

The code means that the vehicle is unable to draw enough vacuum to close the natural vacuum leak detection switch in the vapor canistyer.

Here's where I'd start:

Your purge solenoid is located on the right frame rail near the radiator fan, with the vechicle running you should be able to feel it clicking, if it is inspect the hoses coming off of that, up to the intake manifold and down to the vapor canister for cracking and leaks, you'll likely find one of the rubber hoses along the way is cracked and leaking vacuum, causing the natural vecuum leak detection switch to not close.

If the solenoid is working and you cannot find any cracked hoses you'll likely have a cracked vacuum canister or a faulty nvld assembly, before replacing either of those I'd suggest professional diagnosis.

If you have any further questions let me know, If you're happy with the answer I've provided please click acceptJosh39798.1468802083

It'd be best if you cleared the code with your code reader, though disconnecting the battery should work.

Also, I'm sure you've already checked, but make sure the gas cap is tightly closed and the seal isn't torn.