Originally Posted by
ala_xfire
washing won't help except cosmetically, You have to use wood or plastic scrapers on the old sealant.
Make sure you remove it ALL. Then a very thin bead of RTV all around and around the screw holes too.
Let it cure 24 hours before driving.
You have to clean the grooves thoroughly and the surface, fill the groove evenly all around. An uneven thickness of sealant will set up unevenly and cause uneven drying, some require longer setting times so read the instructions.
Use the correct sealant, not some cheap general usage stuff, it should say sensor safe, not sure if that really matters but good brands are mentioned in this thread.