Brake Booster and Brake Master Cylinder Assembly Overview

Brake Booster and Brake Master Cylinder Assembly Overview

• Brake master cylinder and brake boosters can be replaced independently of one another.






2 - Brake Booster

• On certain vehicles, the necessary pressure is removed at the intake manifold.

• Vehicles with OHBV have a Brake Booster Vacuum Sensor G483 installed. Refer to => [ Brake Booster Vacuum Sensor, with Optimized Hydraulic Brake Vacuum (OHBV) Boosting ] Service and Repair.

Functional Check

• With engine switched off, depress brake pedal firmly several times (to deplete vacuum in tool).

• Press and hold brake pedal.

• Start engine.

• If brake booster is functioning correctly, brake pedal slackens noticeably under foot.

• Disconnect from brake pedal. Refer to => [ Brake Pedal and Brake Booster, Separating ] Brake Pedal and Brake Booster, Separating.

• Removing and installing, refer to => [ Brake Booster ] Brake Booster.

• Removing and installing, TT RS, refer to => [ Brake Booster, TT RS ] Brake Booster, TT RS

• If the vehicle has a TFSI engine, then the noise amplifier must be removed and installed. Refer to => [ Noise Amplifier, TFSI ] Service and Repair.

• If the vehicle has a TTS engine, then the noise amplifier must be removed and installed. Refer to => [ Noise Amplifier, TFSI ] Service and Repair.

• The noise amplifier is inside the engine compartment in front of the brake booster.

• Replace as complete unit if malfunctioning.

1 - Gasket

• For brake booster.

3 - Seal

• Replace

4 - Brake Master Cylinder

• Cannot be serviced.

• Replace as complete unit if malfunctioning.

• Removing and installing, refer to => [ Brake Master Cylinder ] Brake Master Cylinder.

• Removing and installing, TT RS, refer to => [ Brake Master Cylinder, TT RS ] Brake Master Cylinder, TT RS

• If the vehicle has a TFSI engine, then the noise amplifier must be removed and installed. Refer to => [ Noise Amplifier, TFSI ] Service and Repair.

• If the vehicle has a TTS engine, then the noise amplifier must be removed and installed. Refer to => [ Noise Amplifier, TFSI ] Service and Repair.

• The noise amplifier is inside the engine compartment in front of the brake booster.

5 - Heat Shield

• Allocation, refer to the Electronic Parts Catalog (ETKA).

6 - Nut

• Self-locking.

• Always replace after removal.

• 20 Nm

7 - Brake Line

• Brake master cylinder/secondary piston circuit to hydraulic unit.

• 14 Nm

8 - Brake Line

• Brake master cylinder/primary piston circuit to hydraulic control unit.

• 14 Nm

9 - Sealing Plugs

• Coat with brake fluid and insert into brake master cylinder.

10 - Brake Fluid Reservoir

• Coat with brake fluid and insert into sealing plugs in brake master cylinder.

• With floating insert with integrated brake fluid level warning switch.

• To replace the warning switch, remove brake fluid reservoir.

• Press brake fluid reservoir into sealing plugs.

• Removing and installing, refer to => [ Brake Fluid Reservoir ] Service and Repair.

11 - Cap

• With integrated floater and brake fluid level warning switch.

12 - Vacuum Tube

• With check valve.

13 - Sealing Plugs

Check Inner Boot at Brake Booster





- Remove driver side compartment.

- Make sure that boot did not slip out of the circumferential groove, as shown here.

Make sure the brakes are working correctly before driving the vehicle for the first time.