Audi A6 (2011 – 2018) Electric Power Steering Rack

If your Audi A6 (C7, 2011–2018) has thrown a “Steering defective! Do not drive vehicle!” warning, the cause is almost always the electromechanical steering rack. On the A6 the assist motor and control module are built into the rack itself — there is no hydraulic pump — and it is the electronics inside that unit, rather than the mechanical rack, that fail. The A6 is one of the most common cars to show this exact fault, and we repair the original rack and steering ECU at component level, returning your own unit rather than a replacement that shares the same weakness.

The symptoms owners report

The clearest sign is the red “Steering defective! Do not drive vehicle!” message on the cluster. It means exactly what it says — once it is showing, do not keep driving the A6.

• Red “Steering defective! Do not drive vehicle!” warning on the cluster
• Steering suddenly becoming heavy and unassisted, most noticeable at parking and manoeuvring speeds
• Loss of self-centre as you unwind the wheel out of a turn
• The warning appearing intermittently at first, then becoming permanent
• On some A6s the car refuses to start while the fault is active

The fault codes we find

When an affected A6 rack is scanned, two codes recur:

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

Both point inward, to the electronics within the rack rather than to the column, tie rods or wiring — which is why a fault-code read alone rarely persuades a main dealer to do anything short of replacing the whole rack.

What has actually failed

The two failure points sit inside the rack’s integrated steering ECU. The motor position sensor (C10AD29) stops reporting the assist motor’s position reliably, so the module shuts the system down rather than act on data it cannot trust. Separately, the control module’s electronics fail internally (B200049). Mounted low and exposed to heat, vibration and moisture, it is the sensor and control board — not the mechanical rack and pinion — that give out first on a high-mileage A6.

Repairing your A6 rack

Because the failure is in the sensor and control electronics, your A6’s original rack can be repaired at component level rather than written off for a new assembly. This is a mail-in repair-and-return service: our in-house team of electronics engineers carry out circuit-level board repair on the sensor and control module, then return your own unit — repaired to meet or exceed OE specification with the known weak points reinforced. The A6 rack repair is one we handle regularly for private owners and for garages nationwide, and most remanufactured parts carry a lifetime, unlimited-mileage warranty. Keeping the original rack also means its coding is preserved.

After checkout, simply print the repair form, complete your details and include it in the box with your A6 rack — sending it ahead of the unit is fine too. Having it in the box means your rack is logged and ready to work on as soon as it arrives. If you would like to confirm the rack is the right part before you send it, the rest of our electric power steering repair service explains the related parts we handle.