p0446 code, what do I check first?

My check engine light came on this morning and when I got the code read, Autozone said it was p0446 (twice now) and p0441 pending. Should I check the gas cap first to make sure its not defective? The truck has 155k on the original. What are next to look for?

 

They are located under the hood on the right, correct? I think I've seen them before, mine is green.

 

It seems like the gas cap is keeping pressure. When I opened it up, there was the sound of it releasing the pressure in there. This must mean I dont have a hose leak? Start with the VSV (EVAP)?

 

I've noticed lately that the gas pump shuts off every couple gallons when I fill up, that never happened before. Could that be part of this problem? Got the new cap, gotta reset the code and cross my fingers.

 

Is that part replaceable without changing out the canister? I'm going to test the voltage this weekend. Hopefully this is it.

 

The VSV for EVAP and VSV for CCV are under the hood. I believe there is another VSV on the canister.

 

The dealer told me that I could not buy the VSV by the canister without buying the whole thing for $300+! I've found it on Toyota OEM sites online. Do you know of any step by step instructions of replacing the valve?

 

I checked the two VSVs under the hood, they seemed to be working fine. The switch would open and close when I put 9v across them. The canister one didn't click loudly like the others, though I heard a faint sound. Does it sound like it may be bad? It wasn't as audible as the other two. The VSV link said not compatible with Tacomas?

 

^That particular code is more than likely related to the charcoal canister. P0446 is considered a "small" leak in the fuel system, and there is piece on the canister that is faulty by design that fails. It's not the canister that goes bad, but a small plastic piece that cracks and creates the leak that is not replaceable as it's molded into the design of the canister. A new charcoal canister cost around $300 to replace, but it should affect not your driveability or reliability at all, just the annoying orange check light is what you'll have to live with. Considering how many have failed and the exact nature in how they failed, it is beyond me on why Toyota hasn't addressed this issue.

 

The CEL was gone for about 5 days but came on this morning on the way to work. Do you think I should change out the VSV for pressure switching first, since its the cheapest? Or just buy the canister?

 

I ended up taking out the VSV on the canister and it was bad...no clicking when applying a voltage. Got a new one from a junkyard (with a canister), working great now.