Yellow brake warning light on, auto-hold not working

SOURCE: Brake Problem on 2004 VW Passat

You have to get CV Boots replaced, this happens because they split. What happen was something got stuck inside the axel where the little boots is held on and split that little piece of rubber (its easy to do). As a result, fluid leaks and and spashes on the back tires so you never know it happens. When you make turns the car will make a clicking noise. You can add fluid but, it will continue to leak out if those boots are split so, you have to replace the boots. I had to replace the boots and axel because the boots come on the axel. Its an expensive project. Boots, axel and labor $500 starting if you go through the dealer. Also, if you have an extended warranty they won't cover it because there is no time frame when these boots split it just something that can happen. Honestly, they know this is something common especially if you drive through snow.

SOURCE: Removing front calipers to 2003 vw passat w8

go to a tool store and ask for an easy-out, this is a specialty tool placed on a drill to grip stripped screws and broken bolts

SOURCE: ABS/BRAKE warning lights always on in 2000 VW Passat

OKEY TRY TO GET A CODE WITH SCAN TOOL AND IF YOU CANNOT CONTACT WITH YOUR ECM YOU HAVE TO GET FIX YOUR ABS CONTROL UNIT.
BOSH ABS MODULE GIVES PROBLEM ON THAT MODELS I HAVE SAME PROBLEM WITH MY 1999 PASSAT V6 I SENDED MY PART TO GET FIX AND WAITING FOR THE COME BACK.
GOOD LUCK.
I DRAIN THE BRAKE FLUID FOR THE FIX LEAK FROM MY CALIPER AND I REMOVE THE ABS UNIT AND TAKE THE ELECTRONIC MODULE OUT AND SEND THE FOR THE REPAIR.

SOURCE: on 2007 passat 2.0 i replaced rear pads and the

the rear caliper pistons were turned to get them to go back but you could have turned them in too far and the screw that applies the parking brakes could be too far out of adjustment. try turning the piston back out untill you can just get the caliper around the brake pads and see if that helps

SOURCE: VW Passat STOP brake fault warning

Check the fluid level in the resevoir. If it is low then top it up. However, it went low for a reason - maybe it's just because your brake pads starting to wear out or you could possibly have a brake fluid leak.

If your in any doubt have a pro check it out.