JPTL

I currently have the original D90s mounted on my GT and noticed that they were considerably out of balance. Reason being that the black plastic surrounds around the RDK sensors have cracked and come off of the sensor itself.



When looking up part number 928.361.201.02 it looks like they’re called “protection caps”. My guess is that they go on before the RDK sensor is secured to the wheel. Looks like quite a process if that's the case.
Are these necessary?

Brent A.

They can easily be removed and replaced. Takes a bit a force as they "snap" onto the top of the sensor (no adhesive needed as in your picture) but not too difficult. No sense in trying to re-use older ones that have become hard and brittle as they will most likely just split if attempted.
Are they necessary? That's probably a bit debatable but I do think they can provide some protection to the sensor from an kicked up stone. I personally like to keep my car as close as possible to what Porsche had originally intended, so at only $6 each from Roger they are worth it to me.

JPTL

That's the info I was looking for! Thanks for the reply.

StratfordShark

They are installed after torqueing up the nut for the switch, and removed just by twisting 90deg and pulling off.

Have new ones on hand as they become brittle. It can be a job getting nuts off the threads because of corrosion, so I think the caps at least prevent some of this. It’s also fun seeing how people in tyre shops react when they see them!