C058E: Датчик положения мотора усилителя тормозов B — цепь, диапазон или работа

Brake booster motor B's position sensor is reporting an implausible value.

An electric brake booster is what replaced vacuum assistance on cars that have no vacuum to offer.

A petrol engine throttles its intake and produces manifold vacuum as a by-product, and traditional brake servos simply used it. A diesel needs a dedicated pump; a hybrid or electric car, whose engine may be off or absent entirely, has nothing — so the assistance comes from an electric motor pushing the master cylinder directly.

Which makes this motor a genuine safety-critical actuator rather than a convenience. It is a brushless motor with phase windings and a position sensor, controlled precisely, because it is standing between the pedal and the brakes.

Every such system has a mechanical fallback, and knowing it matters. With assistance lost the pedal still acts on the hydraulics directly — so the brakes work, but the pedal becomes very hard and needs far more effort, and stopping distances lengthen considerably. That is a designed failure mode, not a failure of design, and it is why these faults are urgent without being an emergency.

The position sensor is how the controller knows where the motor has pushed the master cylinder to, and therefore how much assistance is actually being delivered. Without a trustworthy position, precise assistance is impossible — so the system withdraws it rather than apply an unknown amount of force to the brakes.

The letter matters here more than usual. A system with two position sensors is using them as a cross-check on a safety-critical actuator, so one failing leaves a car that can still verify itself through the other — which is why the response may be a warning rather than a full fallback. Both failing is a different situation.

Why this page exists when its neighbours do not. Nothing in the public web documents this block — four independent searches established that on 2026-08-10. This code is written because a manufacturer named it, with its definition, in a technical service bulletin filed with the US road safety regulator, and that OEM wording agrees with the standard's own enumeration. Its neighbours have no such document, so they remain undocumented rather than guessed.