The headlight range control system front sender is mounted on the left-hand side of the front subframe, having an arm and link that connect to the left-hand front lower suspension arm, the rear sender is mounted on the rear subframe, with an arm and link connecting with a bracket on the lower transverse link, the system being controlled by an ECU that fits behind a cover on the passenger side of the instrument panel. To be able to remove the front sender, engage the handbrake, jack the front of the car and place the axle supports on the axle stands, remove the front roadwheel and record the position of the sender on the lower arm and then unscrew the nut and disconnect the link and bracket to the lower arm followed by disconnection of the wiring, unscrewing the bolt and removal of the sender on the front subframe. In the case of rear sender, chock the front roadwheels, jacklift the rear of the vehicle and position it on axle stands, and then disconnect wiring of the sender, unscrew the bolts attaching the link and bracket to lower transverse link, and lastly unscrew the bolts to loosen the sender off the rear subframe. Refitting entails undoing the process of removal but with the mounting bolts tightened to the stated torque and where needed, the sender outputs must be verified by an Audi dealer because this task requires special equipment which the home mechanic may not have.