never pressure wash anything that has electronics
this aint your grandpa's c500 lol
blow out with air only
the wires up around the tps and the injectors are very fragile
i had to fix the leads to an assist injector last week that broke off flush to the connector (remove contact pins and solder the wires back on)
they broke from vibrations im assuming
the harnesses in these have had some issues in this area

use the book and the diagnozer together and you should pull through