Harry Bloomfield wrote
David WE Roberts wrote

Top oven (Bosch combi) seems to register about
10 degrees lower than the setting on the knob.

The hysteresis, the difference between it switching
on and switching off, will be at least 10C on such
a thermal switch. I would leave it alone..

Maybe he means that when you set the oven temp
to say 200C, it actually runs the oven at 190C tho.

Not really enough of an error to matter, you'll
get that much variation within the oven.

Even less significant if its F instead of C.