What should be checked before adding brake fluid?

Before adding brake fluid, it is crucial to check the system for leaks and the brake pads for wear. This is important because adding brake fluid without addressing existing issues can lead to further complications. If there is a leak in the brake lines or around the calipers, simply adding fluid may not solve the problem and could lead to a decrease in braking performance, potentially resulting in brake failure.

Additionally, worn brake pads can also impact the braking system's integrity. If the pads are significantly worn down, they may be the cause of low brake fluid levels due to increased fluid displacement when the pads are close to the rotors. Ensuring that both the system is leak-free and the pads are in good condition helps maintain the overall safety and effectiveness of the vehicle’s braking system. This step is essential before any maintenance involving brake fluid to ensure any fluid added is utilized effectively and to prevent overlooking critical safety issues.

The other options, while important for vehicle maintenance, do not directly relate to the assessment of the braking system prior to adding brake fluid.