The customer complains of the warning message in the Driver Information Center of ? Lane change assistant not available? and the button on the mirror does not stay lit. Audi Side Assist is inoperative. Along with the customer complaint, either one or all of the two following DTC? s must be present in the system. Diagnostic Address 19 ? Gateway Control Module (J533) - 02849 Lane Change Assistance Control Module ? J769- 004 No signal/communication - 001 Sporadic. Diagnostic Address 19 ? Gateway Control Module (J533) - 02001 Data Bus Distance control - 004 No signal/communication - 001 Sporadic. Diagnostic Address 3C ? Lane Change Assistance Control Module (J769) - 02071 Local data bus 014 Faulty ? 001 Sporadic. Incorrect component installed at the factory.