Q: Loose headlight clip

A loose clip can allow moisture inside the connection and cause a headlight bulb to stop working, such as what you are experiencing with your Mazda 3. It is also possible that the clip came loose on its own due to damage of the plastic cracking. However I believe the problem may be elsewhere.

Initially, when changing light bulbs, it is extremely important to never touch the glass portion of the bulb with your fingers and only use clean gloves. Your skin’s natural oils can stick to the glass of the bulb. Headlights radiate immense heat and will boil the oil on the glass left by your skin and cause the bulb to burn out prematurely.

Other then these two possibilities, there could be other unknowns in the electrical system issues in the vehicle, such as a short in the wiring. With a situation like this I would recommend enlisting a certified mechanic, such as one from YourMechanic, to stop by and see your vehicle in person and give you a proper diagnosis of why your headlight is not working, allowing your Mazda 3 to run at top notch.