I used a Karcher K3 with foam cannon filled with some generic multipurpose cleaner (made for pressure washer use, I clean floors, furniture, refrigerators with it), sprayed on warm engine (not hot), then attached the VarioPower jet on the Karcher and rinsed thoroughly but not too close. It's a 15 minute workincluding unplugging negative battery lead and drying it before replugging and spraying WD40 on battery connections, and hood retention mechanisms.
I let alone the other electric connectors which are watertight, just don't put too more water pressure on them. Then I wait 5 minutes after rinsing, start the engine, idle 5 minutes and go for a good mixed ride (20km including some fast road). That's for this diesel engine. On petrol I leave idling until the radiator fan kicks in and go for a quick fast road ride.