Safety belts need replacing in the event of mechanical damage or if a car has been crashed. In the latter case, the belts may roll out or in with difficulty or may not roll out or in at all. If the pyrotechnic pretensioners go off (mechanical pretensioners in old-type cars) they need replacing too. To this effect you need to disconnect the battery, the seat belts (the upper and lower mounts and the plastic housing on the internal side of pillar B). Finally, you need to cancel the service errors.