DTC (Trouble code) P0440

[C5Z06]

Took a look at hoses connected to vapor cannister
and two vinyl hoses are melted. Not sure what could
cause this but truck has set P0440 intermittently for
about a year. One hose is about 1/4" in dia. other about
3/4" and goes to vent solenoid. Sent request to gmpartsdirect
but not sure if I can avoid getting ripped by dealer prices on
these parts. They seem to be preformed hard plastic hoses.
I doubt that the Napa stores would carry them. The hoses
seem to have been exposed to excessive heat but can't
think of where or when that could have happened. Vehicle
has 60K miles. Any input from experts appreciated.
Thanks,
Fred

[fishdoktor]

Hi Fred did you ever get the 0440 code to go away? My 2000 GMC is doing the same exact thing. Thanks...........

[maxwedge]

Originally Posted by fishdoktor

Hi Fred did you ever get the 0440 code to go away? My 2000 GMC is doing the same exact thing. Thanks...........

Welcome to AF, look at the thread dates before posting, please, this is 4 years old! BTW a loose or poorly sealing gas cap is the first place to look for this code issue.

[C5Z06]

Never got code figured out. Have gas gauge problem and need to replace fuel pump at some point. Still get P0440 about once a month or so. Clear it and it's ok for several weeks or longer. It's possible it is the filler cap but I don't think so. Once in a while I get a no start and don't know if I hit the gas pedal or not but I need to wait about 10 minutes and then it starts ok.

[C5Z06]

Here we are in 2015 and I still can't figure out the P0440 code that gets set about once a month or so. I have a new AC Delco filler cap and that hasn't kept the code from appearing. Anyone who has had and fixed the P0440 please respond.

Thanks,
Fred

[gmtech1]

No where in your posts do I see a vehicle description for your vehicle. The P0440 can be a tough one to nail down, this is where a bi-directional scan tool and evap test tool and/or smoke machine come in handy. It's possible you have a bad fuel tank pressure sensor, partially sticking vent or purge valve, cracked canister...any leaking seal in the system will cause this.

[C5Z06]

My vehicle is a 1999 GMC Sierra in SLT trim. It has the 5.3 L engine extended cab short bed. Please see my other posts about the fuel tank pressure sensor that I replaced a while ago and offered a method to replace without dropping the fuel tank . The P0440 code started appearing more than 10 years ago and I replaced some hard plastic lines that appeared to be melted due to exposure to heat or chemicals. Since then I've replaced the fuel filler cap/tether with the GM part but that didn't help. I don't have a smoke machine or other more sophisticated tools. Can you give me an estimate of what a dealer is likely to charge to isolate and repair the problem? There doesn't seem to be any effect on performance or operation of my truck. I think another post I made was for P0453 if I remember correctly. I have more than 50 years operating and repairing vehicles and have performed major overhauls of all engine, and drivetrain systems. I hold a degree in electrical engineering and understand the electronics systems used on most vehicles today.
Thanks,
Fred

[gmtech1]

Originally Posted by C5Z06

My vehicle is a 1999 GMC Sierra in SLT trim. It has the 5.3 L engine extended cab short bed. Please see my other posts about the fuel tank pressure sensor that I replaced a while ago and offered a method to replace without dropping the fuel tank . The P0440 code started appearing more than 10 years ago and I replaced some hard plastic lines that appeared to be melted due to exposure to heat or chemicals. Since then I've replaced the fuel filler cap/tether with the GM part but that didn't help. I don't have a smoke machine or other more sophisticated tools. Can you give me an estimate of what a dealer is likely to charge to isolate and repair the problem? There doesn't seem to be any effect on performance or operation of my truck. I think another post I made was for P0453 if I remember correctly. I have more than 50 years operating and repairing vehicles and have performed major overhauls of all engine, and drivetrain systems. I hold a degree in electrical engineering and understand the electronics systems used on most vehicles today.
Thanks,
Fred

Most dealers will charge 1.0hrs labor for this type of diagnosis, so depending on the shop you take it to, your cost will vary. The evap system usually will not cause a noticeable difference in driving. If those damaged line were at the canister, it's possible it was damaged also?

[C5Z06]

OK thanks. At one point the purge valve has failed on at least 3 other GM vehicles I've owned. It may be worth it to replace it just as a wild guess. The cost from Rock Auto is probably under thirty bucks ;-)