Pyrolytic self cleaning program
Turn the oven selector to program 'P' shut the door and switch on the oven. The door will now lock and remain locked until the cleaning cycle is completed. This process takes around 2 hours after which a small pile of ash may be left in the bottom of the oven. Simply wipe this out with a damp cloth when the oven is cool. Please do not use any oven cleaners inside the oven cavity.

Always disconnect your appliance from the mains before you start examining it!