I've got a 07 S4 with Tiptronic and the brake light starting flashing yesterday. I called the Roadside assistance and they towed the car to the dealership. The car is still under warranty but I was wondering what would cause the brake fluild level to fall below the min level. When I checked the brake fluid level I couldn't see any within the brake fluid compartment. The car is only 1.5 years old in terms of use since new and has 29K miles on it. Thanks.

 

UPDATE:

According to the dealer it was just low on brake fluid and they found NO leaks. I'm not sure how brake fluid can get that low without a leak but at least it wasn't anything major.

 

Your pads are probably pretty worn all the way around.

The further out the caliper pistons have to go to push the pads, the more fluid volume is reqired to fill each piston cavity.
Thats why there is a reservoir and not just a sealed system with a set amount of fluid.

Your brake pad light will probably be on soon also