If the light comes on while driving, assume that there is not enough brake fluid and one brake circuit has failed. Then, as a rule, the second brake circuit still remains operational, so if you drive carefully, you will be able to get to the nearest workshop. Our advice: in such a safety-critical unit, you do not necessarily have to trust the automatics - it is better to periodically check yourself whether everything is in order.
Stages of work
The brake fluid expansion tank is located at the height of the front wall under the hood. Check the brake fluid level regularly.
Even with a functioning brake system, the brake fluid level drops. The reason: wear of the brake linings. The pistons come out of the brake collets, the resulting increased volume behind the piston in the cylinders is quickly compensated by the brake fluid.
As long as the brake fluid level in the expansion tank is between the MIN and MAX marks, there is no cause for concern.
Expansion tank with brake fluid