Audi S6 (2011 – 2018) Electric Power Steering Rack

The Audi S6 (C7, 2011–2018) is the performance version of the A6 — a twin-turbo V8 executive that carries real mass over its front axle in both saloon and Avant form. Its steering rack is electromechanical: the assist motor and control module are integrated into the rack, with no hydraulic pump. That motor is under constant load on a car this heavy and this quick, and when the electronics inside the rack fail the steering turns heavy without warning. We repair the S6’s original rack and steering ECU at component level and return the same unit, reinforcing the weak points rather than fitting a like-for-like part that will fail the same way.

What actually fails inside the rack

The failure is electronic, not mechanical. Inside the rack’s integrated steering ECU, the motor position sensor stops reporting the assist motor’s position accurately, and the control module then shuts assistance down because it can no longer trust its own feedback. The control board’s own circuitry can also fail internally. The rack and pinion themselves are almost always sound — it is the sensor and control electronics, fatigued by heat and vibration under a hard-driven V8, that let go.

The fault codes behind it

• C10AD29 — Motor Position Sensor
• B200049 — Internal Control Module Error

Both are internal to the rack’s electronics, which is why replacing tie rods or checking the loom changes nothing, and why a main dealer’s answer is usually a complete new rack.

How it shows on an S6

The warning to watch for is the red “Steering defective! Do not drive vehicle!” message. Take it at face value — stop driving the S6 once it appears.

• Red “Steering defective! Do not drive vehicle!” cluster warning
• Sudden heavy, unassisted steering — the extra front-end mass of the V8 makes the effort very obvious
• Steering wheel no longer self-centring after a turn
• Assistance cutting out intermittently before failing completely

Repair and return — keep your original S6 rack

Because the fault is electronic rather than mechanical, your S6’s original rack can be repaired instead of replaced with a costly complete assembly. Ours is a mail-in repair-and-return service: you send in the failing rack and steering ECU, and our engineers rebuild it in a cleanroom-standard, ESD-safe workshop, carrying out circuit-level repair on the sensor and control module. We return your own unit — repaired to meet or exceed OE specification, with the weak points reinforced — and most remanufactured parts carry a lifetime, unlimited-mileage warranty. Because it is your original rack, its coding is retained and there is no matching against the C7 chassis to worry about.

Once your order is placed, print the repair form, note the codes and symptoms your S6 has shown, and pack it in the box alongside the rack — or send it over to us in advance. It travels with your unit so nothing is missing when the repair starts. Owners who aren’t sure whether the rack is the culprit rather than another steering component can read more across our electric power steering repair service.