Q. Dear Rabbi,
How can I kosher an oven for Pesach?
A. An electric oven should be cleaned very well as far as your hands can reach the refrain from using it for 24 hours. After that you should turn the oven on to its highest heat and leave it on full heat for an hour.
However trays that you bake bread or challah in need to be burned in fire to get the chametz out and since they will get ruined you cannot really kosher them so it is better to have a replacement set for Pesach.
There are also lenient opinions that say immersion in boiling water is sufficient and you can rely on those opinions if you want.
With blessings,
Rabbi Hillel Meyers