These days in almost every car wash outlet you go to, you’ll see one form of pressure washer or the other. Pressure washer is a machine that pressurizes water which flows through it into a powerful force which is so strong that it acts as a sponge or brush. As effective as the pressure-washer maybe in terms of efficiency in washing a car, using it to wash the engine maybe hurting your car without you knowing it.
The engine of a modern car is fitted with sensitive electronics like sensors, wiring harnesses and a whole bunch of other things, which are all connected to the computer which controls the engine. These gadgets runs the risk of being damaged by the shear force of this pressurized water. So if you are doing it, please stop it. Resort to simple cleaning with a cloth