How often do I change the brake sensor

On a 2009 Toyota Corolla, there are no brake sensors or electronic brake wear sensors. The brake pads themselves have a metal tab on them that will rub the brake rotor when enough brake pad material has worn off, allowing the metal tab to rub the rotor and make an audible "squeak" sound. BMW and Mercedes Benz and other vehicles have electronic brake sensors, that, when worn, will complete an electrical circuit and give the driver a warning message or light to inform the driver the brakes are worn. But a 2009 Toyota Corolla is not equipped with this type of system.

What prompted you to ask that question.. 'Brake related' indicator light in instrument cluster remaining on while driving?