The level sensor is within the expansion tank and part of the piece that shows the min/max as it is internal. So it doesn't break like the float in the E38/E39 expansion tanks.


But if yours is still showing low coolant and your at the max with the yellow min/max inside the tank, that is probably broken. However, if you are physically losing coolant and not from the top, like we always saw the white residue on the E38/E39 tanks, it is leaking from a seam on the bottom.

When I replaced mine I capped off the hoses and pressurized the tank with a pressure tester. Then sprayed it with soapy water and found that the seam had a little tiny ass split.

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'01 740i Sport MKIV, Quad Brake Lights, Bi-Xenon retrofit, HID Fogs Dinan 7 Struts, Springs, camber plates, Intake, MAF, CAI, Throttle Body, NBT Retrofit, Strong Strut


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