Peugeot 206 - Central Door Locking Problem

Fault: Central door locking faults including the Central door locking system not operating on one or more doors and the Central door locking system intermittently locking and then immediately unlocking.
Cause: Repeated problems of Central Door Locking (CDL) failure have been traced to water ingress into the harness plug connection to the CDL unit within the door, causing bad corrosion to the terminals. The central locking motor / switch and lock assembly are all encapsulated within one unit, and individual components cannot be renewed separately. It is not possible to diagnose CDL faults by disconnecting solenoids / switches etc because the Built in Systems Interface (BSI) control module logs a fault. Until the fault is rectified the CDL will unlock instantly.