What is code p1720

Hello, P1720 represents an error in communication between the engine control module and other components on the CAN (common area network). Basically, the electronic devices ("computers") in your vehicle talk to each other on a a CAN the same way all of the computers in an office building talk to each other on the local network. A P1720 code just means that is interrupted. You would do well not to attempt repairs on this yourself unless you have a very good understanding of electronic and electric circuits and a professional scan tool. The 7 series is an extremely complex vehicle to diagnose.