Bosch 4.9 heater control

Hi just a quick question. Is the heater element of the sensor supposed to be on all the time ? Or is it a required time after start up to bring it up to temperature faster then shut off?

Thanks

The heater control is always on however the heater is controlled by the wideband controller to maintain a specific operating temperature. In this way it is driven harder when the sensor is cold and heating up and does less once it's at operating temp.