Where is the vapor canister vent valve located?

Hello, the canister vent valve is behind the passenger side rear wheel, it is attached to the canister. The charcoal canister is the big black box next to the fuel tank, you should be able to see it pretty easy. The vent valve is on the side of it. It will have two wires running to its connector. You also be able to identify it by its wire colors. It will have a rubber tube attached to it that is open to the atmosphere. They are not too difficult to change. Did you have a check engine light on for the vent valve? If so, do you remember the code number?

https://www.2carpros.com/articles/how-emission-control-systems-work

Well, the vehicle will run its own EVAP tests at certain times and conditions. The best thing to do is write down every code so you know what you're chasing. For example, there are codes for small EVAP and large EVAP leaks. Codes for the purge valve not functioning. The vent valve is not functioning. Etc. The ECM can set a code according to the reading it gets from the Fuel Tank Pressure sensor when it turns on a certain component. When I have an EVAP system leak I will usually smoke test the system because the leaks can be so small, you'll never find them without a small, pressurized amount of smoke. Without a code for a certain component/ or leak, you have no place to start.
Do you have a scan tool that can read live data? If so, you can look at the Fuel Tank Pressure sensor data PID and see what it's reading while the car is idling. Next to the data PID for that sensor on the scan tool will be a value of the sensor and then a range that the sensor can be in. I'll put some testing below, but really rescan the ECM when the check engine light comes on and write the codes down. Keeping good notes of what you get for readings and codes will help you out a lot if you're learning to be a technician.
Pages 1-6 (each 2 pages is a test for a component) Page 7 is EVAP system Operations, page 8 is the Canister Purge Valve location.
The Vent Valve you first mentioned (I put the diagram up before), is open when the vehicle is turned off. If the Vent Valve was stuck closed due to a failure, you would not be able to pump gas into the tank. That's a sign of a failed Vent valve, because the fuel vapor has no place to go.
The ECM will purge fuel vapor anytime it sees pressure building in the fuel tank from the Fuel Tank Pressure Sensor.
The ECM can also set a leak code if it is purging the fuel tank vapors and does not see a rise in vacuum.
Below is a bunch of information on the whole system. But please write down the codes so we can give specific testing procedures.

You can check the purge valve right at the intake manifold. It will have a vacuum line running to the intake manifold and another hose going back to the charcoal canister. With the Purge Solenoid connector unplugged and the engine running there should be no vacuum being pulled through the purge solenoid. Were you getting vacuum coming threw it with it unplugged?

Thats unfortunate, there have been a lot of bad parts lately. For sensors and solenoid type parts I always get OEM equipment. Was the purge valve solenoid the only code you were getting?

Okay, I just watched both videos, and you're correct, you shouldn't have vacuumed at the Purge valve with it unplugged. The ECM supplies 12 volts to one side of the Purge valve and controls the valve on the Ground side. Where are you getting these valves from? Is it an aftermarket place? The RPMs are jumping around because basically you have a vacuum leak through the purge valve back from the evap system. It's purging when it's not supposed to. Are you positive you have the valve lines hooked up correctly, it's not possible to put the lines on backwards at all? Three bad valves seem unlikely. But I saw you unplug it. This P0443 is a circuit code, So the ECM is monitoring the Control side (Ground side) for the purge valve ECM driver's state. With the valve off, there will be 12 volts on both sides of the valve, when it is energized, the 12 volts on the other wire of the purge valve will go to ground (so around 0 volts). This is a pulse width modulated circuit, so the ECM pulses the ground side to control the solenoid.
The code criteria are Open/High resistance or short to voltage on that control side. Do you have a multimeter? If so, I would see if you have voltage on both pins of the purge valve plug, with it unplugged and key On.
But again, that doesn't explain the vacuum issue.
The other code is being set by the open purge valve.
The fact that the code is a history code at some points indicates it's an intermittent issue.
The orange/black wire is the 12-volt feed at Key On. The other wire is to the ECM.
I don't see any technical service bulletins on this issue either. You might try asking the dealership you got the part from if they have seen an issue like this. To me it looks like a 3rd bad part.
But there is some odd information here, some common repairs for this code are "Replaced Fuel Filler Neck" "Replaced Fuel Receptacle".

I would try tapping lightly on the valve while it's running and see if it closes while it's unplugged. I'm wondering if you're putting the new valve on the car and the ECM is opening it and the vacuum is holding it open somehow. Try turning the car off and leaving the valve unplugged, then start it back up and see if it's still stuck open. Thats the only rational thing I can think of besides another bad valve. I'm assuming you returned the other valves already. This is a strange situation for sure. But try those couple of things and see what happens.

Okay, so, I found an answer, I think. This is from a vent valve stuck open. With outside air pressure being higher than intake manifold pressure, it forces the evap and the positive outside pressure threw the evaps tubing before the ECM can compensate and/or shut the purge valve, so its basically being force fed too much pressure. That is the only thing I can come up with. Try unplugging the Vent Valve and see if the purge valve will stay closed.
If that doesn't work, then we need to consider another point allowing too much out air in, this might be why the filler neck being replaced was a few common fixes for this strange issue.

The filler neck replacement was just in the information we got through All Data and Mitchell. Where we get wiring diagrams and such. There was a record of five times the filler neck was replaced, but that's only when other technicians actually put that information into those data systems. But they would replace it for a leak, yes. You would need a smoke machine to test the evap system for leaks. Thats what we use to detect leaks. But as for that Purge valve, I would check that the purge valve is closed with the engine off. When the car is at a cold start up and the idle is high there is a lot of vacuum pulling in the intake manifold. If that purge valve is closed when the car is off, I would say its okay. The evap system is normally pulled through a small diameter tube and when it's open like that with the evap canister tube off it might be keeping it open. But the code you're getting is a circuit code. So, you need to check if there is any voltage with that purge valve unplugged and just Key On. If you have voltage on both wires, then the control wire is shorted to power somewhere. Thats what the ECM is detecting and setting the code for. It monitors that control wire so it can set those type codes. I just think there's something else going on here, the purge valve might not be opening like that with the tube attached.

One wire is a 12-volt feed the other wire is the control wire which is ground side controlled. With it unplugged and Key On it should have only 12-volts on one side. The testing is below.
I believe the test with it unplugged and the control side reading 2.5-3.5-volts might be a bias voltage for testing. But you have no way to bi-directionally control the solenoid with a scan tool so you can't do the third test.

You can also check the White wire with the Key Off (which is the control wire going to the ECM) with your multimeter set on ohms and see if you have any continuity to battery negative or the engine block (Ground). The orange/black wire is the 12-volt feed to the solenoid. So, if you have 12-volts on both wires with it unplugged then there is a short to power on the white wire somewhere. Or a failed ECM.

You should have 12-volts on orange/black wire and 2.5-3.5 volts on the white wire with it unplugged and Key On. Engine Off.

Well, there's a few possibilities for both of those codes coming back together so fast. The ECM runs a self-test on the evap system at start up. It closes the Purge valve and the Vent valve together. Those are the only 2 valves on this system. With those 2 valves closed it then watches the Fuel Tank Pressure sensor to see if too much vacuum is developing during a pre-set amount of time. Thats how the p0496 code is set. The Code description is "Fuel Tank Pressure Sensor indicates vacuum during a non-purge condition". I'm assuming you had 12 volts (or battery power) on the orange/black wire with the Key On. And 2.9 volts on the other White wire.
Those are correct readings.
The P0443 is the ECM either detecting something wrong on the Control wire (white wire) for whatever reason, Short to Ground, Short to power, Or open circuit. But you don't seem to have any of those. If you did, you would not be getting the 2.9 volts. If it were a short to ground, it would be 0 volts. Short to power you would have 12v. Open circuit you would have OL on your meter. And yes, a failed ECM can do all kinds of things. But before condemning the ECM you would have to check all of its Powers(12v) and Ground connections. Thats a rule of thumb before condemning a module. Plus, they can be very expensive. At this point considering you are low on the diagnostic equipment a shop would have, I think I would try 1 more purge valve from the dealership if they will give you a trade in. But this time, tell them what's going on, Every detail. Dealerships will see these type of issues more than any other shop would. They might know right away what is the most common cause for both of these codes together.
To be honest the running condition for the P0496 is that the P0443 is Not Set. I don't want to guess what is happening and have you replaced an ECM just to have the same codes come back again. At that point you will be beyond frustrated. You wouldn't even be able to replace the ECM because they need to be programmed to the VIN.
On both of our databases if the voltage readings are within limits, it replaces the ECM, but that is always a definite last thing we want to do.
But I think you should ask the dealership if they have seen this issue, there is no technical service bulletins yet for this because the car is probably not old enough and they haven't seen this issue enough to send out a TSB on it.
I wondered too, if you erase both codes, does the P0443 come back at just Key On or do you have to run the car first and then they both come back? And the fact that the car is stumbling and stalling, that tells me that there really is a problem somewhere and this might not just be an ECM glitching out on you.
So, after all that, try one more purge valve, see what the dealership might say before we go testing all the powers and grounds to the ECM.

One extra thought here, I had someone suggest checking the new Purge valve before you return it for any pieces of the charcoal canister in the valve keeping it open. I hadn't thought of that. A failed charcoal canister with debris going through the evap hoses. Or even take the canister off and shake it, see if any pieces fall out.

Here is a picture of a failed charcoal canister. It can be caused by overfilling the gas tank after the handle has already auto-shut off.
This also explains the codes, the purge valve is actually stuck open and that is completing the circuit, so the ECM will see 12 volts on the control side without commanding the valve on causing the p0443. The flow without being commanded on is causing the p0496.

If that new valve happens to be stuck open, which I think it is, that would be the only logical reason for both codes to come up like that. 11 volts sounds low, especially if that is running. You should check the charging system while it's running too, just see what you have for voltage across the battery. Turn the headlights on so there is some load, you should have at least 13-14volts, even 11 with the car off is too low. Do you know if the purge valve is stuck open? I know it's extremely odd to get so many faulty valves, Bosch is the OEM for Chevrolet. So, it should be a good brand, unless they're getting a different brand.

I finally found a TSB on the Evap system, I know this isn't the code you're getting but they are having issues with the Purge valves, this TSB didn't show up on my other searches for some reason. They have a very specific testing procedure for the evap system on this car. So, if that new valve isn't bad, there must be another reason for releasing a bulletin on it. That valve shouldn't be opening like it is. They are showing even if the valve is not leaking to remove it from the vehicle and do a pressure test of the rest of the tank and system. Ask about this also when getting a new valve from the dealership, this is an updated TSB.