The halogen bulb needs to be replaced.
To replace the bulb, proceed as follows:
Disconnect the appliance from the power supply.
Loosen the bulb cover with the tool supplied at the back of the frame.
Remove the halogen bulb.
Replace the defective bulb with a new halogen bulb (Sylvania 66740 120 V 40 W, G9, FS1).
Press the bulb cover back into place.
Reconnect the oven to its electrical supply.