Code P445

[BobBilly]

I have been getting Code P445, for three years, I have a 2005 GMC Yukon, 5.3, 235000 miles, at 231K I put a long block from Rockauto in and it runs like new. The only issue I still have is this P445 code. I have replaced the Gas cap with a new GM Cap three times to no avail. I have performed a smoke test and found nothing leaking.
Does anyone have any suggestion?

 

[treehan77]

Have you checked the vent valve or purge valve? Hopefully you don’t have charcoal pellets all the way up to the purge valve. If you do, probably gonna have to end up dropping the whole gas tank to blow out the lines. Charcoal canister might be toast.

 

[Fless]

Have you checked the vent valve or purge valve? Hopefully you don’t have charcoal pellets all the way up to the purge valve. If you do, probably gonna have to end up dropping the whole gas tank to blow out the lines. Charcoal canister might be toast.

^^^ THIS And you need a bidirectional scanner like a Tech 2 to do a purge and seal of the evap system. Depending on the vacuum decay you can tell if it's a larger or smaller leak.

You can also test your canister vent valve to make sure it's closing when the ignition is on (apply 12v to the connector while trying to push air through it).

Ultimately you may have to smoke the system to see what's leaking.

 

[George B]

A scanner will be critical diagnosing this.

 

[treehan77]

Bench test any replacement parts before install- I received a genuine AC delco vent valve that was defective out of the box

 

[Rocket Man]

P0445 is for the purge valve. Replace it and see if the code goes away. The evap system is one of the most frustrating to work on. I have a Tech2 and still had a hard time diagnosing mine because it was random, sometimes wouldn't happen (small leak) for a month or 2. I ended up replacing the gas cap, vent valve, purge valve and canister one by one.

 

[George B]

Sometimes the tank pressure sensor can be flakey too.

 

[Fless]

I am currently working on this, too. New gas cap, purge solenoid, vent valve, and canister. The vent valve was bad, staying closed intermittently with the ignition off, but that wouldn't cause this. Still have the leak. My youngest will bring a smoke machine over soon and hopefully we'll find the problem. We did the fuel pump nearly two years ago and all has been well until the last month or so. If we can't find it I have a great shop to give some business.

 

[treehan77]

Filler neck hose could be rotted also

 

[Fless]

Filler neck hose could be rotted also

At this point it could be just about anything on mine. We don't have much rust here and I tightened up all of the hose clamps that go to the filler neck.