When a sign is used in addition to a price indicator, as defined in Section 13470, and if the same grade of motor vehicle fuel is sold at a different price from any other dispenser on the same premises, it shall be unlawful to display the sign on a dispenser unless a sign with price numerals of equal size is displayed upon each dispenser from which the same grade of motor vehicle fuel is dispensed at higher prices.
Ca. Bus. and Prof'l. Code § 13472