It can take a while for drivers to realize that their headlights are badly adjusted – not everyone has an eye for small discrepancies. There will often need to be major changes before drivers begin to consider what the cause could be. One obvious sign that something is wrong is when oncoming cars begin to flash their lights in protest at being dazzled. But why does this suddenly occur?
When the driver has recently done an headlight adjustment with a faulty bulb, the reason is pretty obvious: either the new or old bulb wasn’t constructed to within the proper tolerances. In a headlight, the filament of an automotive bulb needs to be correctly positioned to within a hundredth of a millimeter to ensure the light is delivered to precisely the right part of the road ahead.
With Osram bulbs, the quality of the manufacturing process ensures that this is the case. However, problems may still arise when an Osram bulb is being used to replace one that wasn’t produced with the same degree of precision. A headlight that has been adjusted for the older bulb won’t deliver the correct light distribution with the new (and better) bulb. Generally speaking, the only way to avoid headlight readjustment is by replacing the older bulb with one of the same quality. By the way, this readjustment work costs considerably more than the difference in price between a quality bulb and a no-name product.
Bulbs that have been incorrectly fitted can also aim the beam at the wrong part of the road. The socket of a headlight bulb needs to be located precisely in the correct position, not just somewhere in the general vicinity. However, despite the provided clips, catches or bayonet mounts, inexperienced owners can sometimes make serious mistakes when changing bulbs without the necessary care and attention. Once that happens, simply readjusting the headlight isn’t going to be enough.
Lamp replacements are not always the reason for incorrectly adjusted headlights, of course. Even the most innocuous of collisions can cause a slight shift in the mounting location within the car body. Expensive repairs are not always necessary though, and garages may be able to fix such problems through realignment. Headlight leveling errors, where the lamps remain in the lowest position, are much more annoying, and the luminous range becomes a real issue. In cases of this kind, repairing the leveling system is the only way to avoid driving blind.