There are a few reasons for this. One is the most obvious and that is the child lock switch needs to be engaged to unlock.Some models call it panel lock.
Turning the panel lock on and off:
To turn the panel lock on, press and hold the Panel Lock key for four seconds. The Panel Lock symbol will appear in the display.
To turn the panel lock off, press and hold the Panel Lock key for four seconds. The message in the display will disappear.
The lenses unscrew anti-clockwise, but they can be very stiff and difficult to grip. The best advice I can give you is to double or triple wrap a thick elastic-band around the lens as this will give you much better grip than you will get on the glass alone.
If you are still unable to unscrew the lens, squirt a small amount of WD40 / penetrating fluid down the back of the lens so it runs onto the threads and leave it for 15-20 minutes then try again with the elastic-band grip. Once the lens moves a small amount it will unscrew relatively easily. The constant heating and cooling of the oven causes them to lock.
Please switch off the power supply to the oven before replacing the bulb and make sure you have clean hands when replacing the bulb - grease from your fingers can cause the bulb to fail or shorten its life considerably.
Hope this helps. If you are still unable to unscrew the lens, please let me know.
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TUTORIALS1, If the Bosch fan motorin the back of the oven is going round and
the temperature light is on (normally little red light), but there is no heat
then you will probably need a new oven element, these are generally very easy
to fit and readily available from our website these can be tested with a
electric meter. To gain access to the BOSCHelement you will
have to remove the back plate from inside the oven. Once removed you will see
the fan and element, if you
look closely at the elementyou will
probably see a small hole burnt in it where it has blown. Sometimes however
there is no evidence of a fault but the elementis open circuit ie:
broken inside the element casing, either way it will need replacing. Some
elements will are fixed from inside the oven and some are held in place by nuts
from the rear of the machine. 2, If your BOSCH fan
oven is getting warm but takes a very long time to cook or is burning the food
more on one side than the other, then you need to check if your oven fan motoris working you will
see the blade turning fast if it is ok. if the element is heating but the fan motoris not blowing the heat into the oven then
you need To replace the oven fan motoris a little more
expensive and a bit more involved. 3. If you have the opposite problem ie: your oven is over heating
and burning everything then you will need to replace your BOSCH oven thermostat 4, A quite common and easily overlooked answer is if your BOSCH oven is not working at all ie: no
heat and no fan then the chances are that someone has put the oven timerinto AUTO mode,
simply put oven back to MANUAL mode and all should be working again.
