I'd guess a dodgy electrical connection. Look for corrosion on the connections and particularly the earth connection.

Could be the bulb itself, look at it closely you might see the filament is unattached at one end, when you tap it the thing makes contact and stays there whilst its hot, if this is the case the bulb glass will most likely be smoke stained inside.

Assuming these arn't HID bulbs a standard H4 or H7 bulb is very cheap so no harm in trying one, if its an HID bulb and it needs one suggest finding the Philips equivalent (one of daughter's Civics is HID equipped) @ around £32, the Honda parts desk being over £100.

Edited by gordonbennet on 10/03/2023 at 07:56

Thanks for updating the thread, so many don't.

Its good for the money saving knowledge for all of us these days if we've put our collective bonces together come up with some suggestions.