ASE G1 Auto Maintenance and Light RepairBrakesEasy
A technician is inspecting a vehicle's brake system. The brake pedal feels spongy and goes almost to the floor before the brakes engage. Which of the following is the MOST likely cause?
- AAir in the hydraulic system
- BWorn brake pads
- CA seized brake caliper
- DA faulty brake booster
Show answer & explanationAnswer & explanation
Correct answer: A. Air in the hydraulic system
Air in the hydraulic system is compressible, unlike brake fluid. When air is present, the pedal will feel spongy and may travel further before building pressure, leading to a low pedal.
Why the other options are wrong
- B. Worn brake pads typically cause a harder pedal or a grinding sound, not a spongy low pedal.
- C. A seized brake caliper would likely cause the wheel to drag, excessive heat, or a pull to one side, not a spongy pedal.
- D. A faulty brake booster would result in a hard pedal requiring more effort, not a spongy or low pedal.
Brake Pedal Sponginess
A condition where the brake pedal feels soft and travels excessively before the brakes engage, often indicating a problem with hydraulic pressure.
- Most commonly caused by air in the brake lines.
- Can also be caused by contaminated fluid or a faulty master cylinder.
- Requires bleeding the brake system to remove air.
Memory trick: Air in the lines makes the pedal feel like a soft cloud.