Coolant Level Sensor

[Beamer619]

My expansion tank coolant level goes down in coolant every time I fill it up and drive the car. The level senor on then expansion tank is not sending the warning to the dash when the coolant level is below the sensor. I guessing the sensor is bad, is there anyway to test it. I couldn't see any test in the service manual.

[shogun]

levelling switch 61311378320 L=109MM is a very simple float https://www.amazon.com/URO-Parts-61-.../dp/B00U0WTN42
check if the float is filled with water that it does not go up, or if the contacts are oxidized. If that is o.k., removed the 2 wire connector and make a wire bridge between these 2 pins on the wire loom side, then the light should go on. If not, wire broken, or the plug housing is damaged that the pins retract. Plug housing 61131378408 https://www.fcpeuro.com/products/bmw...ng-61131378408