why does my BMW 3 Series G20/G21 (2019-2024) brake pedal go to the floor?

Solution

1. Preparation

• Gather all necessary tools and parts.
• Ensure the vehicle is parked on a flat surface and the engine is off.
• Wear safety goggles and gloves.

2. Inspect and Replace Brake Fluid

• Remove the cap from the brake fluid reservoir.
• Tools Required: Brake fluid, funnel.
• Sub-steps:
  1. If the brake fluid is low, top it off with the manufacturer's recommended brake fluid type.
  2. Check for contamination in the fluid; replace if necessary.

3. Repair or Replace Leaking Components

• Inspect brake lines, calipers, and connections for leaks.
• Tools Required: Wrench set, brake line tool.
• Sub-steps:
  1. If a leak is identified, tighten loose fittings or replace damaged lines or calipers.
  2. Ensure all connections are secure and free of leaks.

4. Bleed the Brake System

• Prepare a brake bleeder kit or a helper to assist.
• Tools Required: Brake bleeder kit, wrench.
• Sub-steps:
  1. Begin at the farthest brake from the master cylinder (usually the rear passenger side).
  2. Attach the bleeder hose to the caliper bleeder valve and open the valve.
  3. Have a helper pump the brake pedal until no air bubbles appear, then close the valve.
  4. Repeat for all brakes in the order (rear passenger, rear driver, front passenger, front driver).

5. Inspect and Replace Brake Pads and Rotors

• If pads or rotors are worn, they must be replaced.
• Tools Required: Jack, jack stands, socket set, torque wrench.
• Sub-steps:
  1. Lift the vehicle and secure it with jack stands.
  2. Remove the wheel and inspect the brake pads and rotors.
  3. If worn, remove the caliper and replace the pads and/or rotors.
  4. Reinstall the caliper and wheel, then lower the vehicle.