1. Master cylinder failure. The master cylinder is responsible for creating the hydraulic pressure that pushes the brake fluid to the calipers and wheel cylinders. If the master cylinder is faulty, it may not be able to create enough pressure, causing the brake pedal to sink to the floor.
2. Brake booster failure. The brake booster assists the driver in applying pressure to the brake pedal. If the brake booster is faulty, it may not be able to provide enough assistance, making it difficult to stop the vehicle and causing the brake pedal to sink to the floor.
3. Air in the brake lines. Air in the brake lines can cause a spongy brake pedal and reduce braking effectiveness. This can happen if the brake lines have been opened for any reason, such as to replace a brake caliper or wheel cylinder.
4. Leaking brake lines or calipers. A leak in the brake lines or calipers can allow brake fluid to escape, reducing the pressure in the system and causing the brake pedal to sink to the floor.
To diagnose the problem, you will need to inspect the brake system for any of these issues. Once you have identified the cause, you can then repair or replace the faulty component. If you are not comfortable working on your own brakes, you should take your vehicle to a qualified mechanic.
