About two months after buying the truck I had multiple evap. emission codes popping up for a small evap leak. P0442, P0441 and a P0456 while on a road trip. Tested every emissions valve, smoked the system, took the charcoal canister out and cleaned out the valves, replaced the VSV solenoid attached to the charcoal canister and gas cap. Code kept coming back though. Watching the flow reading with the charcoal canister air vent clamped off and saw the flow to stop meaning the issue was likely the mechanical vacuum valve that parts of the canister assembly. Unfortunately cleaning the dirt and debris out of it did not fix it so I had to shell out $400 for a new factory canister.
The code requires two drive cycles on a gas tank less then 3/4 or more then 1/4 full for the system to test/set the codes.
The blue body vacuum switching valve(VSV) that is attached to the charcoal canister (circled in red)does fail and IS replaceable without buying a new canister.
https://www.amazon.com/dp/B00NFJIIIE?ref_=ppx_hzsearch_conn_dt_b_fed_asin_title_1 OR just get the actual part number off the valve, the replacement is sold as a late model Camry part. The charcoal canister is located above the spare tire.
UPDATE
I got a chance to tear down the valve I suspected was the point of failure. They are removable but as far as I understand they are not replaceable separate from the entire canister but I really wanted to know how the valve worked, failed, and if it was possibly repairable because the tanks are kind of pricey.
The above picture is the business end of the charcoal canister. I thought the failure was going to be dirt lodged in the valve seal on the circled assembly. The port with the arrow pointing at it is the fresh air vent. During testing clamping off this hose made the flow meter on the smoke machine drop to zero. At rest this valve should be sealed to venting air is my understanding. The end caps of the diaphragms are friction welded on so I had to cut the tops off to see what was going on inside.
This is the upper section of the diaphragm with the top cut off. The diaphragm apparently tore hence the dust inside the top cap.
Unfortunately there is no repair option as the diaphragm is just worn out and cracking around the center sealing disk. What's interesting is the valve seems counter intuitive in its function if its purpose was to seal off the fresh air vent which is the port in the center on the picture above.
However what does make sense is why its registering a very small leak. Inside the fresh air vent port there is a small hole that leads into the top of the diaphragm. The tear in the diaphragm rubber allows evap gasses to pass through into the top of the diaphragm and out the fresh air vent. Sucks it cannot be fixed but at least I now know how it fails and how to properly test it in the future.
