Service Engine Soon - P0446

[dkraines]

I have a 2000 1/2T Suburban. What's the likely cause to throw a P0446 code (EVAP Emission Control System Vent Circuit Malfunction). Gas cap was on tight.

Where is the canister and related release solenoid on this vehicle?
Edit: OK I found these mounted by the gas tank.

Is P0446 thrown from a vacuum leak test or a vacuum release test?

I also researched someone saying to clean the filter on the vent release, this would imply a vacuum release test failed. Someone else said the newer vent solenoid houses a bigger filter (what is the GM Part for this?).

Comments?

Any help greatly appreciated.

[dkraines]

Reply to self...

my quick fix attempt.

OK, it is very easy to get to the sponge filter on the EVAP vent release valve (located at the rear of the gas tank):

1. Push the valve/filter assemble back off of the metal tab (on the bracket) it rests on, being careful not to damage the hose and wires. No need to get the hose off or wires, as this can be done while attached to the vehicle. I didn't even need to jack up the vehicle.
2. Flip it around 180, piviting on the hose assembly, and pop the 4 release tabs to get the filter cap off. Careful, don't break those tabs.
3. A bunch of fine dirt came out of mine. Pull the sponge out.
4. I washed the sponge under water and let it dry.
5. Tapped the dirt out from the recepticle, and wiped clean.
6. Put everything back in reverse order

Time: About 25 minutes, 10 of which was spent figuring out if I wanted to disconnect the assembly. The hose clamp is some strange contraption puzzle.

One cautious note: The sponge is undersized for the enclosure, which "maybe" could let dirt pass through. Apparently GM used some sponge from an existing application, as it was clearly not specifically engineered for this application. The concern, of course, is that dirt may make it to the EVAP canister, maybe to the intake manifold (hopefully not because hopfully there are other filters before the IM). Also the sponge is fairly porous, and I question it's filtering capability.

Will keep you posted if it fixes the issue (P0446). If not, I will probably take it to the dealer for them to test (I bet they have a nice machine that tests this).

I believe this should be a regular serviced filter in dusty conditions, but no mention can I find in the owner's manual. I am also going to keep my eye out for a bigger piece of sponge filter I can cut to fit.

Cheers