In some cases, the engine belt idler pulley bolt could loosen and/or break. As such, the belt may become detached, resulting in a sudden loss of power steering assist. The system would then revert to a manual steering mode, which would require greater effort from the driver, especially at low vehicle speeds.
As a result, BMW Canada dealers will replace the idler pulley bolt and tighten with a revised torque procedure. A thread locking compound will be applied to the replacement bolt.
Source: Transports Canada