Can't give you much guidence - will be either regulator or the plate itself. no easy way to find out. you will have to remove the hob top and check for continuity thro the plate. ifplate is ok, then power up and check for supply to the plate. if no supply, then the regulator will be at fault

I am having the same problem have you found a solution yet?
My front left hob does not seem to detect the pan. It shows f