maintains
v.v. to keep something in good condition by checking it and fixing it regularly. It can also mean to continue saying that something is true, even if other people do not believe you.
v. to preserve something in its existing state or condition through routine care and repair; alternatively, to assert a position or claim steadfastly in the face of opposition. Transitive — requires a direct object or a 'that' clause.
He maintains his car by changing the oil every month.
The city council maintains the public parks to ensure they remain safe and attractive for local families.
Despite the overwhelming evidence presented by the prosecution, the defendant maintains that he was nowhere near the scene of the crime on the night in question.
The verb is transitive and takes a direct object when referring to upkeep, or a 'that' clause when expressing an opinion or assertion.
He maintains of his houseHe maintains his houseMaintain is a transitive verb and does not take a preposition like 'of' before its object.