Thermador will not ignite and no gas to left burners

My thermador range PRDS484GGUS has no gas going to the left 2 burners which are the extra low burners. The right burners have gas. None of the burners ignite. The only way I get the right burners to light is to use a lighter. Could this be a spark ignitor problem? Any help would be great so I do not have to purchase a new unit.