Have you checked the gas cap? Is it tight?

 

Have you checked the gas cap? Is it tight?

I checked it. It looks OK. When I open the gas cap slowly, I heard some hissing sound. I think the gas cap is holding pressure.

 

read my post about clearing this code only earlier thread....toyota had a problem as I did w/ my closed canister valve, located in back of air filter canister, cost 60 at dealership....good luck.

 

Found some TSBs but ended up replacing the charcoal canister.

 

Mine had several codes, intermittent, so I kept monitoring it, and a man on SiennaClub found out by parts swapping between his two siennas that it was the canister, so that also fixed mine.

 

In case anyone isn't familiar, and you're getting these codes, the P0440 through P0446 are all codes that refer to the evaporative emissions system, the system that keeps fuel system vapors (eg. gasoline vapors) from escaping the vehicle.

After testing all the components of my 2002 Sienna's EVAP system (valves, hoses, etc), I changed the charcoal canister. This solved the problem, and my evaporative system codes have not returned. I now have an audible hiss when I open my gas cap, which had previously been rare. Replacing the charcoal canister wasn't difficult, but the nuts and bolts holding things together were very rusty, after living on the underside of the van for 8 years. Be sure to spray yours with a good rust-removing oil (I used Kroil), and be patient, so you don't sheer off a bolt. I purchased my canister on eBay, from a Toyota dealer in Ohio for about $225.

 

Great job!

 

I've replaced charcoal canisters twice now. The mechanical non-electrical valves seem to go bad. These are the round ones with the diaphragms. I've seen an article where someone has rebuilt the electric valve on the canister (which can be removed without taking off the whole canister). This one can be tested by applying 12v like the others. If it is not this valve, the it is likely the diaphragm valves and those cannot be bought separately. The cost for the canister (with all three valves) is around $250 or so.

 

Just got this code today in our 03 Symphony. Changing gas cap first - will advise and update thread...

 

Good luck with this. Hopefully, it's only debris, as in ply's TSB. Be sure to get a bunch of good penetrating oil for the bolts down under!

 

Well, so far a new OEM gas cap has seemed to fix the issue....

 

Is your EVAP monitor "ready" already?