aka Reference Mark Sensor - 2 flat pins/spade connectors located inside recessed plug
When this part fails, it causes a "No start" condition, generally when the engine is hot. It may work again when the engine is cold but, will again fail at operating temperature.
Manufactured in Germany by VNE Automotive, the OEM supplier to Mercedes. VNE is a lesser known manufacturer than the bigger electronics suppliers, such as Bosch and Hella however, Mercedes has chosen them as a principal supplier.