after-sales service
repairs of cars, electrical household appliances and other consumer goods made for benefit of own clients by producer or retailer.

diagnostic
application area for systems specialized in failures, errors or irregularities identification as for hardware or software | all messages sent by computer to operator in order to report errors in controls use

maintenance
all operations that have to maintain efficient and good conditions of some installation, device, road, construction, etc.; maintenance costs; lift is out of use for maintenance operations

activate
make active or more active; get working; put in action; put in motion some machine; activate blood circulation | prepare for operation: activate the mine.