Mines is a 2015, its not really a knock its more of an on and off kind of scraping noise like somethings rubbing , but yours does sound like a knock, has yours been fine the whole time?
yea. I think mines one of the polly belt tentioners. Maybe start by looking there as you can reach them. Give them a wobble see if they move ?? Then I'd get it to a garage incase it's something a little more serious