CAN (Controller Area Network) is a twisted pair (2-wire) serial bus network to allow devices to comunicate with each other. In the past most configurable devices were accesible via the L-wire, later K-wire and at the end even two K-wires. The K-wire is going to get replaced by the CAN bus to reduce the number of wires and enable the various devices to talk to each other. Instead of having a single wire for light, ignition, speed, reverse and other signals, two wires (CAN high/low) are sufficient today. In newer Audis, several devices are only accessible via K-wire. Most of the engine controllers, the phone interface, MMI in the A6/A8, they are all CAN only devices not supporting communication via K-wire anymore.