BMW 328d Clicking noises under car at shutdown anfromd startup

Came back from a long trip and pulled the car into the garage where I heard a consistent click from under the car about once every 5 seconds. Shut it down and came back with my phone later and couldn’t replicate the issue but I was able to get it to produce these clicks on shutting it off and turning it back on. The clicking sounds like relays or valves.