Download Audi V8, Audi A8 GEAR BOX CONTROL UNIT. GEAR BOX CONTROL UNIT MODELS AFFECTED: Audi V8 from ‘91 & A8 from ‘94 FAULT: 018 gearbox the ATF cooler pipe connection leaks at gearbox. CAUSE: The ATF cooler pipe vibrates this causes the pipe adapter at the gear box to leak. SOLUTION: Do not replace control unit. It is possible to code with VAG 1551 with a workshop code smaller than 655 36.