The present invention relates to a CAN module configured to be arranged between a CAN controller and a CAN transceiver. The CAN module received a TXD input signal from the CAN controller and is configured to transmit an TXD output signal to the CAN transceiver, wherein the TXD output signal is adapted by the CAN module to also comprising a test impulse. When monitoring the CAN BUS, the CAN transceiver will feed back an RDX signal to the CAN module and the CAN controller. The CAN module is configured to detect an error on the CAN transceiver or the CAN BUS depending on the transmitted test impulse and the test impulse received via the RDX signal. The present inventio also relates to a system comprising the CAN module and a method for the CAN module.