Dash Warning Light

[BoB s-line]

I have a warning light that came on the other day. It is a circle with a small square over it and a red X thru the circle. It is not in my owner's manual, but after looking on the web the closest symbol I can find is a light issue. I checked all of my lights - Headlights, brake lights, back-up lights, etc. and all are working. I've attached a picture of the symbol. What is another way to track down the problem?
Thanks in advance