Capteur de position du moteur non calibré après remplacement

A drive motor, inverter or rotor position sensor has been replaced and the calibration routine that follows it has not been run. Nothing is broken. A step was skipped — and the reason it matters is not obvious, which is why it gets skipped.

An inverter produces torque by placing a rotating magnetic field just ahead of the rotor's magnets, so it must know exactly where the rotor is at every instant. The position sensor reports rotor angle, but the sensor's own zero is not the rotor's magnetic zero. The offset between the two depends on how that particular sensor ended up mounted on that particular machine — a fraction of a degree of manufacturing and assembly tolerance. It cannot be assumed, and it is not built in. It is measured once, on the vehicle, and stored.

Replace any of the three parts and the stored value describes an arrangement that no longer exists.

The symptom is what makes this worth recognising, because it does not look like a fault at all. The car works. It simply works badly: the field is placed approximately rather than exactly, so the machine produces less torque for more current, runs hotter, and returns worse efficiency and range. A vehicle back from motor or inverter work that feels flat and drinks the battery is very often this — and because the obvious conclusion is that the new part is faulty, the usual response is to replace it again, which changes nothing and invalidates the calibration a second time.

The fix is a scan tool routine, not a component. It belongs to the same family as the throttle relearn and the transmission adaptation reset: cheap, quick, and invisible to anybody who does not know it exists.