Error code P0440

Hi,

This code is not for the canister itself. It is for a large leak in the evap system. I attached the code detail and description so that we can figure this out. There is also the testing that you will need to run through to find the leak. Basically you are going to pull it into a vacuum and if it doesn't hold it then you have an active leak vs one that is not currently leaking. Then you just separate the system and test the vacuum until it holds a vacuum and you know the section you just past contains the issue.

Let me know what you find and we can go from there. Thanks

The most common cause for the P0440 code on a GM like yours is the vent valve solenoid that is mounted under the truck. This is the EVAP vent valve. It lets air into the fuel system as fuel is pumped into the tank. Plus it allows for the tank to equalize pressure. It looks like the picture and is mounted above the fuel tank on the cross member behind the fuel tank. If this is a 2 door or 4 door with an under body spare tire the vent will be above it.
The valve has a 2 pin wiring connector and the vent line has a quick connect on the end and it clips into the bracket on the frame.
The valve is really easy to replace if you are not in a rust belt area.