Written by the BS Auto Supplies LLC Editorial Team | Reviewed by the BS Auto Supplies Parts Team | Last updated: September 30, 2026 Quick Answer: Why Is Your Mazda CX-9 Left Headlight Not Working? Why is my Mazda CX-9 left headlight not working? The usual culprits are a burned-out bulb or LED module, a blown fuse, a faulty relay, a corroded connector, a bad ground, or a cracked,...