How do I fix error code 05-53 (outer cam switch always open) in a model CD-100C?

SOURCE: will not start up has

i think it is a igniter failure but as its a gas appliance i would not recommend a home repair because if its not correct and you play with something and their is an explosion then your house insurance is invalidated ,also you could kill yourself if the flue is blocked with carbon monoxide the best advice here is to call a certified engineer and pay the bill ,also to get him to check it over so you obtain a certificate as if anything does happen you are covered on the insurance then.