Brake booster?

Hello, today while in a parking lot, me pedal suddenly went down, whoosh!!! and back to normal. This happened a number of times on the way home. No fault codes in brake booster, brake assist or brake abs. I had a little gray, but after this I have alot of gray. Is this a booster, master or some other problem? This is dangerous and I have parked the car until this is solved. Thank-you for your help, Nick

Check the vacuum lines first.

Thank-you. The noise this is making sounds like the air brake replief valve on a semi. It is coming from under the dash where the pedal is. This is why I think it is the booster. Is there a procedure for checking the booster? When appling thr btake it will grab the brake for s split second, dump some air pressure, and the pedal will act somewhat normal.

Read this!!!!! Does this sound like your problem???

Yes, that sounds like my situation. That part number is the brake booster? I am going to call the dealer tomorrow. I can't believe this failed in 3 years. I can't believe there isn't a safety recall on this. It does sound right except my tires don't lock up. I think that means that my ABS is working properly. As soon as it senses a lock up, the pressure is released and I have to apply the brakes again. Very scary! Nick

My 2002 TDI has this problem too. I will make sure they replace the brake booster. Thanks!!