Ok the buzzing/clicking is only supposed to last for 30/ seconds or so each time you switch the ignition on as all the actuators do a test sweep open and closed a couple of times.
I have seen throttle housings fail, but unlike a petrol engine, they are only there on a diesel as a shut-off valve so the engine stops nice and smooth, so failure doesn't usually manifest in any other driveability issues unless it's stuck closed.
It's easy enough to pull the airbox and intercooler hose and visibly check the throttle actuator if you don't have access to Vida.
The EGR position sensor and motor are the assembly that the throttle housing is mounted to, and if the EGR is not closing properly then it will continue to buzz.
I usually check this function on Vida as it's easier to spot an issue and often it intermittently gets stuck.
Are you chasing any particular issues with the car or just curious about the noise?