Brake booster check valve

[dewana421]

I cannot locate the brake booster check valve in my 2008 Lexus ES 350. 
I brake is very hard to press and I’m trying to troubleshoot whether it is the check valve that is bad or the brake booster itself. I manually try to vacuum on the brake booster, but it did not work however, when I turn the car on the brake perfectly works fine. The only issue I’m facing is that the break is very hard to press as soon as I turn the car off. Which tells me that the vacuum is leaking somewhere.  
I just want to eliminate the check valve, but cannot locate it anywhere. Normally it’s located on the vacuum hose that goes from the intake manifold to the brake booster but on this car, there is no check valve on that pipe and I did check that vacuum pipe which has no leaks. 
Seems like it is a pretty common problem on this car, but I have not seen any issues on YouTube or anywhere. Please share what you found on yours.

[RX400h]

Quote

I understand your concern about the brake booster check valve in your 2008 Lexus ES 350. It seems like you’ve done a thorough job of troubleshooting the issue.

The brake booster check valve is typically located on the brake booster assembly. However, it appears that locating the check valve in a 2008 Lexus ES 350 might be a bit tricky.

According to a Lexus parts website, the part number for the Power Brake Booster Check Valve for a Lexus ES 350 (2007 - 2020) is 4473028030. You might want to consider contacting a Lexus dealership or a knowledgeable Lexus technician for support.

As for the hard brake pedal issue, it’s indeed a common problem with the Lexus ES 350. The issue could be due to various reasons such as worn brake pads, contaminated brake fluid, or broken brake rotors. If the problem persists after checking the brake booster and the check valve, it might be worth having a professional mechanic inspect your vehicle.