electric cooktop burner comes on by itself even when knob is in off position

I have a KitchenAid glasstop electric cooktop. It’s a 30" model KECC507BBL1. The large ,rear left burner will come on and heat up for a few seconds and then turn off, all by itself even when the control knob is in the off position. Any advice you can give me, including part numbers would be a great help. Also do you think it’s worth repairing?

ledith