They play a big role in stopping your car and play an even bigger role in making sure you are safe travelling in a vehicle. For this reason, they must be replaced as soon as you notice signs of them failing and not working as they are required. Some signs that indicate a need for replacement of these lines are; When you step on the brake pedal, it might feel spongy or soft due to uneven pressure in the system. This is due to leakage of the brake fluid. Another sign is a lack of braking power even when you press the brake pedal hard. Also, when you notice leakages when inspecting the lines, that means they should be replaced.