Method for Monitoring at Least One Y-Capacitance of an Electrical On-Board Power Supply of a Vehicle, and Electrical On-Board Power Supply

A method for monitoring at least one Y-capacitance of an electrical on-board power supply of a vehicle includes ascertaining a current capacitance value of the at least one Y-capacitance and a current on-board power supply voltage of the electrical on-board power supply. The method further includes determining a currently stored amount of energy in the at least one Y-capacitance depending on the current on-board power supply voltage of the electrical on-board power supply and the current capacitance value of the at least one Y-capacitance of the electrical on-board power supply, comparing the currently stored amount of energy in the at least one Y-capacitance to a predetermined threshold value, and generating a control signal when the predetermined threshold value is exceeded in the comparing.