Method and system for diagnosing MVB (Multifunction Vehicle Bus) communication fault

The invention discloses a method for diagnosing an MVB (Multifunction Vehicle Bus) communication fault. The method comprises the following steps: acquiring a transmission message on an MVB bus in real time; the method comprises the following steps of: decoding a transmission message, recording an analysis state indicating whether the current MVB communication is decoded and/or checked correctly, and then positioning and diagnosing an analysis type fault or a data content type fault of the current MVB communication according to the analysis state and/or frame data obtained after decoding under the condition that the previous decoding is correct and checked correctly. Writing the fault positioning data into a register; and when the received message type is a life signal port data request, sending the fault positioning data in the register to an MVB network through the life signal port data so as to be received by a central processing unit in the network. According to the invention, on the basis of not increasin