The control unit, especially a motor vehicle control unit, includes a microcomputer (13), a programmable nonvolatile memory (14) connected with or integrated in the microcomputer (13), a serial interface (15) for the microcomputer (13) to which a serial data transmission line (12) can be connected over which data for programming the programmable nonvolatile memory (14) is received in the microcomputer from an external programming unit (11), and a low pass filter connected to a terminal (16) for the serial data transmission line. The low pass filter includes components that produce a signal for enabling the programming of the programmable nonvolatile memory (14) of the external programming unit is connected to the control unit via the serial data transmission line (12). These components preferably include a first resistor (R2) connected between the terminal (16) and a programming-enabling input (19) of the microcomputer (13), a capacitor (C1) connected between the programming-enabling input (19) and ground and a second resistor (R1) connected to ground between the capacitor (C1) and the programming-enabling input.