2019 M3 sr+. recently the horn was working intermittently, then stopped working completely. Dash-cam still saves when pressed so I assume the problem is not in the steering wheel. I replaced the horns myself with 3rd party universal horns. First test the horn worked great. 2 days later the horn has stopped again. Research on the existence and or location of a horn fuse or relay has not been fruitful. Some say the m3 doesn't use one and some say it does but doesn't show where it would be located. I hear the m3 horn has lots of issues but not on how to fix.