Can a lock cylinder be replaced without changing the whole door?

Often, yes. A compatible euro cylinder can usually be changed independently of the door and multipoint mechanism. Correct length, fixing position, function and door setup matter; not every cylinder fits every door.

Do not order by appearance alone. Have the existing cylinder measured or ask a locksmith to confirm the suitable size and type. The cylinder may be separately replaceable, but correct dimensions and compatibility matter.

The lock case, multipoint strip and door can remain in place if they are working and suitable. A cylinder that projects too far or has the wrong cam can create operational and security issues. Confirm the exact measurement from the fixing screw to each end before selecting a product; if unsure, ask a locksmith to identify it.