If you have problems with your car's brakes, these are the most common faults

Basically, the faults affecting the braking system can be related to the discs, the pads, the calipers, the hydraulic circuit or the anti-lock braking system ABS. If your car is properly maintained, with the checks carried out at the MOT, it is normally easy to detect a brake problem. But if you notice “strange” things in the pedal, there may be a fault that needs to be fixed immediately. These are the most common problems and the faults that brake systems present.

1.- Glazed or dirty pads

Many cars have a brake pad wear indicator, which warns with a warning light on the dashboard that it is time to replace them. But not all cars are like this, so it is advisable to carry out periodic inspections. However, a very common brake fault is the presence of dirt on the pads, usually grease or oil, as well as their glazing, depending on the quality of the pads and the work they are subjected to. This is very easy to detect, as the pedal feel clearly becomes harder, although a hard pedal can also be caused by a malfunctioning brake servo, or damage to the discs. Be very careful with worn pads, because if you push it too far, you may also have to replace the discs prematurely.

2.- The circuit has air bubbles or blockages

In this article we discussed the importance of replacing the brake fluid when the manufacturer indicates, something very few users do. We also explained what happens if you don’t change it. Brake fluid is key to the proper functioning of the system. If the hydraulic circuit has any deformation in the lines, for example due to impacts, this can prevent the fluid from flowing correctly, reducing the system’s effectiveness. There can also be air or water bubbles in the circuit, which contaminate the brake fluid, causing it to lose its properties and making the pedal feel spongier, or reducing braking efficiency. The solution is usually a bleeding, or replacing the fluid if it is more than two years old.

3.- Warped discs: vibrations and noises

When we notice that braking transmits a vibration through the pedal or the steering wheel, it is very likely that the brake discs have warped. This usually happens because the discs wear out, but also due to irregular operation of the system (calipers or pistons), or from subjecting the brakes to excessive work, in which very sudden temperature changes have occurred. Be very careful, because this can cause damage to the transmission or steering system; it is advisable to replace them as soon as possible.

4.- Seized or leaking calipers and pistons

One of the greatest enemies of the brake system pistons is dirt and rust, which can cause the calipers to malfunction, with fluid leaks, or even the pistons seizing as they become stuck in their housing. Driving with worn pads or discs, using an inappropriate fluid, or the deformation of the guide pins due to incorrect installation or to intense and prolonged braking effort can cause this fault.

5.- ABS faults

When any of the above happens, the ABS may malfunction until we fix it. But the ABS can also behave abnormally due to faults within the anti-lock braking system itself. For example, faults in the control unit, which does not correctly interpret the data. Another possibility is that the solenoid valves responsible for modulating pressure are the ones failing. As for the wheel sensors, although they are usually well protected, a knock or excessive dirt (be careful if you drive off-road) can affect their operation.

Related information of interest

• Learn to identify faults from tyre wear
• Timing belt: the failure most feared by drivers
• Ten reasons why your car could fail the MOT