BHAI I washed my swift engine twice last year. Just by covering ecu with plastic sheet and get the engine bay cleaned.
Note that service station guy put his hand in front of water nozzle to reduce pressure and I left the battery and ecu place from wasing. Just cleaned that area with pressured air at the service station paying 50 rs xtra and cleaned it my self to achieve the satisfaction
But b b b very careful as ecu is very sensitive and I took the risk