Vehicle electrical system and method for protecting a vehicle electrical system

A method for protecting an on-board electrical system of a motor vehicle, wherein the on-board electrical system comprises a current distributor and a plurality of first lines, which are configured to connect a corresponding plurality of first lines to the current distributor, wherein the on-board electrical system comprises a plurality of semiconductor-based first switching elements for the corresponding plurality of electrical components, wherein a specified first switching element of a specified first line is configured to interrupt the specified first line, and wherein the on-board electrical system comprises a second line, which is configured to connect the current distributor to the on-board electrical system, and a limiting unit, which is configured to limit or to prevent a second current on the second line and/or to change a second voltage on the second line, the method comprising:

• determining that the specified first switching element does not open even though a first current through the specified first switching element exceeds a first current threshold value;
• and,
• in response to the determining, prompting the limiting unit to limit or to prevent the second current on the second line and/or to reduce the second voltage on the second line, wherein:
• the limiting unit has a superordinate current threshold value from which the second current on the second line is automatically limited or prevented;
• and
• the method further comprises prompting the limiting unit to limit or to prevent the second current on the second line even if the second current has not yet reached the superordinate current threshold value.