Inversor de potencia defectuoso

The power electronics that turn the battery's direct current into the three-phase alternating current that drives the motors — and back again when braking. It is one of the most expensive electrical components on the vehicle, which is exactly why it should be the last name left on a diagnosis rather than the first.

Most of what gets blamed on the inverter is something nearer the surface. Its own cooling loop failing makes a healthy inverter misbehave; a poor twelve-volt supply or earth makes its control side fail self-checks; its current sensors drift and report phantom faults; and software updates have fixed real fleets of these codes without a part being fitted. Some models have had inverter recalls, so a check for open campaigns by chassis number is free and occasionally covers the whole repair.

When the inverter genuinely fails, it is usually the switching stage for one phase — which shows as phase-current codes for one phase rather than vague misbehaviour, and an insulation test of the motor rules the other expensive suspect out before anything is ordered.