NVLD = Natural Vacuum Leak Detection


You have a pump under the truck that basically constantly tests the vacuum lines and system to make sure there isn't a leak.

Give that a check and go from there

 

I had the same codes. Look under the truck on the drivers side right in front of the gas tank. There will be a box looking thing with some wires and a bunch of hoses connected to it. That's your leak detection pump. Check all those hoses. Mine was dry rotted right at the pump with a big crack at the connection.

 

Just replaced the nvld pump and new filter along with the 2 hoses. Cleared the codes and seems to be running better. Only time will tell from here it depends on if the light stays off for ever or comes back on . Do you think this could have affected my mpg or no?

 

Should the hose that connects the 2 canisters together be replaced? Has anyone ever had it go out or rot and crack?

 

Alright guys well I went about 300 miles in 1 trip and my check engine light just came back on. Got home threw the scanner on and P0440 came back. What could be the next thing to look into?

 

Should I maybe try a gas cap I read? It's about 3 years old and from napa auto parts. Should I get one from the dealer?

 

was it just the p0440 that came back? I replaced the hoses i bought bulk hoses from oreilys for like 7 and just cut to fit with a pocket knife cheap enough to just replace. Did you put the hoses back onto the nvld pump correctly? The only other things aside form hoses would be the purge solenoid (under hood near fuse box i believe) or the charcoal canister (black plastic box under the truck in metal cage near nvld pump).

 

Yes p0440 is the only code. I made sure to install all hoses correctly. I replaced purge silanoid about a year ago .

 

I also have read it could be hoses connecting to purge silanoid I sill look st those today

 

Use the brake cleaner method on all components you installed/replaced that will tell you if there is still a leak.

If you don't find a leak using that method then replace your gas cap with a new one and see if that code comes back.

That code is a minor EVAP leak so you shouldn't see too many problems, you might see a slightly erratic idle RPM if it is actually a leak, if it is just the gas cap then you shouldn't see any RPM fluctuation at Idle.

If you are getting odd shifting or coasting to a stop the RPM becomes erratic then you have a vacuum leak which is likely the purge solenoid.

Do us a favor and update your garage by clicking on the little thing under your name in your posts that says "Garage is empty, add now". It will help out in the future