Missing low coolant level warning
 

I'm facing strange issue with my X5 4.4i (M62TU). When coolant radiator and expansion tank are empty I don't have any warning message on the dashboard. But when I disconnect plug from coolant sensor in expansion tank, then CHECK COOLANT LEVEL warning is there, so it looks like wiring harness is fine. My coolant expansion tank is new (OE BMW 7514964), I've also replaced coolant sensor (also OE BMW 7553919) but the issue is still there. Do you have an ideas what's wrong, why there is no warning when coolant level is low?

Good day!

Well, this is a strange one indeed... The only thing I can come up with is that you have a pin stuck in the connector and it is making a bridge across to the other pin when connected to any sensor... Not connected, you lose that pin from the sensor to complete the circuit... !??!!?

Maybe?!!

Good luck and let us know what you discover...

Cheers!!!

Seen this thread....?

https://xoutpost.com/bmw-sav-forums/...l-message.html

Not quite your issue but it might help....

This thread is very helpful, now I know the way sensor works, thanks :)
I've performed one more test - I've removed the sensor from the tank without disconnecting the plug and then warning message appeared. So it looks like the tank causes the issue, maybe the magnet has been stuck somehow.
Am I right that if I push the float down with my finger then the warning message should appear?

Yes it should make the message appear.

OK, so it clearly means that there is something wrong with my coolant tank, I have to replace it again.
Thanks a lot guys for your help :thumbup: