Checking for leaks by pressing the brake pedal (Audi Q5-8R)

Turn off the engine. Until then, press the brake pedal until there is brake force support, "brake booster works idle", the brake pedal becomes hard. Press the brake pedal (move the pedal approximately 20 mm from its original position). Maintain constant pedal pressure for about 20 seconds. Pedal travel should not increase. Release the brake pedal. Press the brake pedal firmly with your foot. Maintain constant pedal pressure for about 20 seconds. Pedal travel should not increase. If the brake pedal fails during any of the checks, repeat the visual inspection of the brake system (main brake cylinder, brake hoses, hydraulic unit and brake calipers). The hydraulic pump on the hydraulic unit cannot be replaced. If no leaks were found during the inspection, then it is highly likely that the main brake cylinder is leaky and should be replaced. When replacing the main brake cylinder, brake fluid should not get into the brake booster.

(The original text of the material can be found on the website audimanual.ru)