A method for protecting configuration data from a data bus transceiver operable in a subnetwork mode. The configuration data are provided for comparison with data bus message data arriving via a data bus. A reference checksum for the configuration data is generated and stored, and recurrently checked. In the event of an identified alteration, a wake-up signal and/or a piece of error information is output. During or after writing the configuration data to a configuration register via the data bus or directly before the change to the low-power mode of the electronic control unit, a checksum unit forms a checksum that is stored in a reference register. In the low-power mode of the electronic control unit, the checksum for the configuration is repeatedly recomputed and compared with the checksum stored in the reference register. If the recomputed checksum does not match the stored checksum, a wake-up process is triggered.