P0455 and P0441 codes?

Hello, Evap leaks can be difficult and time consuming for sure. Ill post the service info on these codes, the P0455 is a "Gross Evap Leak" so a large leak compared to the smaller leak codes hopefully wont be as bad. The P0441 is an incorrect Purge flow code, so the fuel tank pressure wasnt changing like it should when the ECM runs its self tests on the Evap system. So a couple things, I start with a visual inspection of all the Evap hoses I can get to and I just check for loose hose clamps, (where the hose clamp is not tight enough and the hose can be spun by hand). If nothing stands out, Ill move on to a smoke test as well, but while smoke testing I will also spray hoses and fittings with soapy water. Dish soap works best. Soapy water will start to bubble up leaks that can be missed by just a smoke test.
Make sure the Purge valve is sealed. You shouldnt be able to blow any air through it when its inactive.
And depending on the smoke machine you have and how long it will run, mine shuts off smoke after so long, but will still push the 0.5psi of testing pressure, and this is where the soapy water will help. What work was done recently and how long after the repairs did the codes show up?

Ok so the new codes took a couple days to set because they take 2 key cycles to set. Sounds like a project car you're getting going.
I would pull up the live scan tool data for the engine and see what the Fuel Tank Pressure sensor(FTPS) is reading at idle. If the pressure sensor starts to read negative without any Purge Valve command On, check to see there is no intake manifold vacuum being pulled through the valve. Depending on the design, I usually just put a vacuum gauge right on the purge valve and see if theres any vacuum starting to pull at idle and higher RPMs.
Another tool that can be extremely helpful is using a borescope camera to be able to look into areas you couldnt normally, such as on top of the gas tank if its difficult to see when checking for smoke.
A capable scan tool should be able to run bi-directional controls on the vehicle, so you can close sections of the Evap and break the system down some when looking for leaks.
Heres the service info for the P0455 code, Toyota uses a leak detection pump, Ill post wiring diagrams for it as well.
One thing to keep in mind is the ECM will pull the gas tank into a vacuum and seal it for testing, so thats negative pressure, but these systems can leak differently when under positive pressure. So hoses pushing out verses being pulled in by manifold vacuum. Ill continue to post some more info for you.

https://www.2carpros.com/articles/evap-system-code-repair

Diagrams 1 and 2 (top & bottom) are wiring diagrams which include the Evap System Leak Detection Pump, the Evap Canister Pressure Sensor (this is also known as a "Fuel Tank Pressure Sensor"), and then the service info for the P0441 code. I know these can really get frustrating, but remember to block off sections of the Evap and divide up the testing, that way youre not trying to search the entire vehicle at one time. Let us know what you find.

If the diagrams dont load on my posts, please let us know asap so we can address any issues, Im not seeing the diagrams fully loaded here.

Ok I apologize, I will attempt to reload them all.

To begin with, these are the Evap Leak Detection Pump wiring diagrams, I will post the oem diagrams as well. Soon as we get these other diagrams to post correctly, we've been making some technical adjustments here.

Yeah I can see not even one is loading now, I apologize greatly for these technical issues, the boss is aware of the problems, I may be able to send you some info via email for a temporary basis, at least you can get some wiring diagrams that way, if you want to try that? Leave me an email address here or message me. I will attempt to send you a private message.

I just tried to send you a private message, did you receive it? Might have to look for the messaging service section.

Ok sent something for a test

Ok I can see things are still not posting here. Sorry for the delay, Im not sure I even got a notification for this message, but your scan tool gave you an error when you went to run this Evap test? This Evap VSV (vacuum switching valve) is the Purge valve. This test on your scan tool looks like a "Service Bay" type of I/M Readiness monitor option to run the Evap leak test without having to do the long drive cycles that the emissions monitors take to do, if it fails or backs out of that test on your scan tool, then the ECM is most likely seeing an active fault in the system. Every manufacturer is different when it comes to how they program their ECMs to run self tests like this, I would check the Purge valve first and see if its stuck open or closed.
This Key-Off Monitor is listed in service info I sent you, under "Monitor Description". The ECM has to run and pass each system, such as Oxygen sensor monitors, Catalyst Monitor, Heated Oxygen sensor monitor, Evap Monitor, Misfire Monitor, etc. It will run each of these self tests (monitors) while you are driving under different conditions. Most are run in a certain order, for example theres no point in running a Catalytic converter monitor if there are cylinder misfires happening, hopefully that makes sense. With this setup though, having much of the Evap system contained in the Canister with the leak detection pump, pressure sensor, Vent valve and Canister, with the Purge valve being in the engine compartment, the system is not spread out all over the place like some are. Ill send some other info on the valves location.
The Evap system might not run that test you were trying without the vehicle running. Since it will usually start off with using intake manifold vacuum to pull the Evap vapor system into a vacuum as well, then seal the system and monitor the fuel tank pressure sensor for any loss of pressure or vacuum. It also usually runs this test at highway (55-60mph) cruising speeds when its running it under normal mode, and not being commanded on by a scan tool. It should give you instructions to follow regarding the test too.