What could cause a soft brake pedal?

A soft brake pedal can be a significant indicator of an issue within the braking system, and moisture in the brake fluid is a plausible cause. Brake fluid is hygroscopic, meaning it absorbs moisture from the air over time. When moisture enters the brake fluid, it lowers the boiling point of the fluid. This can lead to the formation of vapor bubbles when the brakes are applied, which compresses the vapor rather than the fluid itself. As a result, the braking force may not be transmitted effectively, resulting in a soft or spongy feel when pressing the brake pedal.

In contrast, worn brake pads primarily affect stopping power and may lead to a grinding noise, but they do not typically cause a soft pedal feel. Incorrect tire pressure affects vehicle handling and tire wear, but it does not impact the feel or function of the brake pedal directly. A faulty ignition system can disrupt the engine’s performance but has no bearing on the hydraulic brake system and therefore does not relate to the condition of the brake pedal. Understanding these distinctions is essential for diagnosing brake-related issues effectively.