Clean the brake lines with a cleaning agent.
Caution: The brake lines are coated with a layer of polyethylene to protect against corrosion. If this layer is damaged, corrosion of the lines may occur. For this reason, the brake lines must not be cleaned with a wire brush, sandpaper or screwdriver.
Light the brake lines from the master brake cylinder to the ABS unit and from it to the individual wheel brake cylinders with a lamp and check. The master brake cylinder is located in the engine compartment under the brake fluid expansion tank.
Brake pipes must not be bent or twisted. They must not show any signs of rust or abrasion. Otherwise, the entire pipe up to the next connector must be replaced.
Brake hoses connect the brake pipes to the wheel brake cylinders located on the moving parts of the car. They are made of a material that can withstand high pressure, but over time they can become porous, swell, or be cut by sharp objects. In all such cases, the brake hoses must be replaced immediately.
To detect damage, bend the brake hoses by hand in all directions. Brake hoses must not be twisted (if there is one, pay attention to the colored control line!).
Turn the steering wheel to the right and left until it stops. The brake hoses should not touch any parts of the car in any position.
The connection points of the brake pipes and hoses must not have any traces of protruding brake fluid.
Lower the car.