Boot Locking Actuator

What is a Boot Locking Actuator?
The boot locking actuator is an electrical/mechanical component that controls the locking and unlocking of the boot lib/hatch.

When the actuators fail it can be a major problem opening the boot up.
What problems can be caused by this part?

Boot central locking mechanism does not work correctly

When pressing one of the various buttons (keyfob, inside car, on boot lid) the boot lock doesn't release and the boot does not open.

How much does it cost to replace the Boot Locking Actuator?
They tend to cost from around £20 to replace for cheaper units.
We have 23 owner problems that mention the Boot Locking Actuator