Audi S5 (2011 – 2018) Electric Power Steering Rack

The Audi S5 (B8, 2011–2018) is the supercharged performance version of the A5, and the “Steering defective! Do not drive vehicle!” fault is well documented on it — often as a complete shutdown of assistance. The S5’s steering rack is electromechanical, with the assist motor and control module built into the rack rather than fed by a hydraulic pump, and the failure is in those internal electronics rather than the mechanical rack. We repair the S5’s original rack and steering ECU at component level and return your own unit, reinforced against the fault recurring.

The symptoms on an S5

The warning to look for is the red “Steering defective! Do not drive vehicle!” message on the cluster. Take it literally — do not continue driving the S5 once it appears.

• Red “Steering defective! Do not drive vehicle!” cluster warning
• Steering going heavy and unassisted, most obvious at parking and low speeds
• Steering wheel that no longer self-centres after a turn
• A sudden, complete loss of assistance rather than a gradual fade
• On some cars, a no-start alongside the warning

The fault codes

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

Both are internal to the rack’s electronics, not the column, tie rods or loom — which is why a dealer scan usually ends with a quote for a complete new rack.

What actually fails

The failure points are inside the rack’s integrated steering ECU. The motor position sensor (C10AD29) stops reporting the assist motor’s position reliably, so the control module shuts assistance down rather than act on feedback it cannot trust. The control board’s own circuitry can also fail internally (B200049). On a hard-worked supercharged coupe, it is the sensor and control electronics — fatigued by heat and vibration — that fail first, while the rack and pinion stay sound.

Repair-and-return for your S5 rack

Because the fault is in the internal electronics rather than the mechanical rack, your S5’s original unit can be repaired at component level instead of replaced. Ours is a mail-in repair-and-return service: our in-house engineers carry out circuit-level board repair on the sensor and control module, and every unit is proven on our Hardware-in-the-Loop rigs — which simulate real heat, vibration and load — before we return your own rack, repaired to meet or exceed OE specification with the weak points reinforced. Most remanufactured parts carry a lifetime, unlimited-mileage warranty, and your original coding is retained. Because the S5 so often loses assistance completely rather than fading gradually, the car is usually undriveable by the time the fault is confirmed, which is exactly why removing the rack and posting it to us tends to be the most practical route back to a properly steering car.

After you have checked out, print the repair form, note what your S5 has been doing, and include it in the box with the rack — sending it ahead works just as well. It keeps your details with the unit so the repair starts the moment it arrives. Owners unsure whether the rack is the fault rather than another component can see more on our electric power steering repair service.