After starting my 2009 BMW R1200GS the fuel guage showed over half a tank, it was warming up and then the low fuel warning light came on. The fuel guage is completely blank, no bars at all. Any thoughts on the problem?

It is a known issue with the low fuel warning light.. You need a mobile auto electrician with a $5,000 scan tool computer. It will pinpoint all the issues with the various modules..

https://www.google.com/search?q=Mercedes+SLK.+The+low+fuel+warning+light+is+always+on

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Sounds like a faulty sending unit in the tank. I believe your car's pump and sending unit may be accessible from inside your car (as in the accompanying video) I am looking for but haven't found one of your exact model, but haven't given up either. BMW fuel pump how to replace

most fuel gauge readings are not that accurate anyway so its out of fuel but not what the is guage reading. but the fuel level sensor in the tank may be at fault sound like its the prob but the instument pack should put the low fuel light on if its fitted on your vehicle spec but not always fitted even though the warning light is present hope this helps

I suggest you read the vehicle owner's handbook to be certain what the exact function of the light is. You will need to know that in order to determine whether the light is warning you or is broken.

The fuel light usually warns the fuel level in the tank is low...

A loose connection on the sending unit could cause the problem but also moisture in the tank in cold weather could also be a factor in which i would add fuel line antifreeze to a full tank of fuel..........Hope this helps you out.