I have a 2002 buick lesabre and recently the check engine light came on. The code is p0440.
I have read why this code came on and would like to know where on the vehicle the vapor canister and valve is located.
The guy at autozone looked at my gas cap and said it looked fine.
Any help will be appreciated.

2002 Buick Lesabre - GM0305301 Fuel Supply System L364HP69
Its under the vehicle in front of the gas tank. Hope the pic helps.

Thread title was revised to properly highlight the original poster'* question.

Thanks. The picture was clear enough. Now for an amateur to see if he can find a leak.

alot of times its road junk in the vent valve, the valve wont close and its taken as a leak

You might want to read this as well:

https://www.gmforum.com/obd-ii-troub.../p0440-284087/

Currently just had the same code on my 03.

The vacuum for the evap test starts on the engine at the right side of the car from the fuel pressure regulator. The switch there turns on the vacuum. Check the vacuum line from the intake to the switch there. I found mine was cracked at the U-turn area, leaking apparently. The switch there can be removed and tested: with 12 volts it opens and applies vacuum through the line going to the rear of the car. I was told you should be able to blow air through it while the 12 v is on.

At the rear the evap cannister has a large tube and switch that is normally open and applying 12 volt there should seal it so you can't breath through it.

The car applies the test roughly when engine temp is less than 89 deg. F and fuel tank level is measured between 15 and 85%. Speed needs to be less than 75 mph. And a couple of other parameters that tell the computer it can run the check for integrity of the fuel system seal.

If it'* not able to apply vacuum for the amount and time that is specified, the code is set. So mine was apprently loss of vacuum at the U in the vacuum hose on the engine. I had twisted that part of the hose trying to take the tube off when I did my fuel pressure regulator and it cracked because it was hardened.