The brake suddenly lost braking power after the brake pedal was depressed at a red light on a local street. Every time I press the brake pedal after the incident, I could hear a sound of air leaking somewhere behind the pedal. Other systems seem fine and I managed to roll the car back to our parking lot about half a mile away, and had the car tolled to a local dealer the next day. I was told later by the dealer that it's caused by malfunction of brake "booster" or vacuum pump(?) and repaired it at a cost of ~$2500

- San Diego, CA, USA