Also detail engine bay with a simple green spray down then a wash with a foaming tire cleaner from armor all as a final cleaning process. Let it foam up an coat everything then wipe everything down with lots of clean rags.
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Auto detailers for dealers use a pressure washer on the motor and then when it’s dry spray everything underhood with “no touch” tire shine.. it’s foolproof and won’t harm sensors/wires or make your belts squeak, as the “no touch” name implies you just spray and forget.
For sun damaged (yellowed) plastic (polycarbonate) headlight lenses you will need 1200 or higher grit wet/dry sandpaper and a high speed buffer and plastic polish (maguires , blue coral etc.) .
I would never use a power washer on the engine or electrical components. I only use a garden hose with a light spray. I do at times hook the hose to the hot water side of my shop sink an use a spray nozzle but never a high pressure power washer inside the engine bay.
May get away with it a few times but I won’t do such with my vehicles.
The no touch spray shine sounds like same concept