What is a common indicator of air in the brake system?

A spongy brake pedal feel is a common indicator of air present in the brake system. When air becomes introduced into the hydraulic brake system, it compresses more easily than brake fluid, leading to a loss of the firm feedback that is expected when the brake pedal is engaged. Instead of a solid feel, the pedal may feel soft or spongy when pressed, indicating that the hydraulic system is not working as efficiently as it should. This is why a spongy brake pedal is a critical symptom for technicians to recognize, as it often suggests that the brake system needs to be bled to remove any trapped air and restore optimal performance.

High brake fluid levels, rapid pedal response, and fluid discoloration do not specifically indicate the presence of air in the system. High fluid levels might indicate an overfilled reservoir but are not a sign of air. Rapid pedal response is associated with a properly functioning system, and fluid discoloration may point to contamination rather than an air issue.