Show all / Hide all

If one headlight lamp fails, does the other need to be replaced at the same time?

Headlight lamps should always be replaced in pairs. With halogen lamps, in particular, it is worth replacing the second lamp at the same time because if the two lamps were installed together, the second lamp will also be nearing the end of its life. What is more, replacing the two lamps at the same time ensures that the light delivered by the left and right headlights is of equal brightness and quality.

What do the markings on an automotive lamp mean?

The law requires that approved lamps should display the following information: manufacturer, rated voltage, wattage, certification mark (e.g. E1) and approval mark. The individual printed markings on the lamp are as follows:

• The manufacturer's name or a clear abbreviation.
• 12 or 12V, 24 or 24V indicates the rated voltage according to ECE Regulation 37. 55W, for example, indicates the rated power in watts. H4, H7, P21W, etc., are the standard international categories for ECE standardised amps.
• E1 indicates the country in which the lamp has been tested and approved. Light sources approved in Germany display a "1".
• A capital "U" indicates a UV-reduced lamp in accordance with ECE requirements. Such lamps are used, for example, in plastic headlights. Brand lamps fulfil these requirements.
• If DOT appears on a lamp, it means that the lamp is approved for the US market. This identifier is required only for main headlight lamps – low and high beam.
• Finally, every lamp displays the approval mark of the relevant authority; in the case of E1, this is the Federal Motor Transport Authority in Flensburg. The approval mark consists of either 37R (E1) + a 5-digit number or just (E1) + a 3-digit number. In most cases, lamps also display the manufacturer's own code to facilitate production batch tracking.

Are there incandescent lamps that last the life of an automobile?

High-quality brand incandescent lamps have a long life nowadays. But even they cannot burn for ever. That is impossible because of the laws of physics. Incandescent lamps work with a filament, which slowly evaporates when a current passes through it. After a certain number of operating hours, the filament inevitably burns through and the lamp needs to be replaced.

Theoretically, incandescent headlight lamps could be designed to have an extremely long life. But that longevity would be gained at the expense of safety. This is because either the filament would have to operate at a lower temperature or the tungsten wire used to make it would need to be thicker. Either way, the result would be a considerable reduction of luminous efficacy and inadequate distribution of light over the roadway.

Why do headlight lamps need to be "UV-reduced"?

Modern headlights have lots of plastic parts, because plastics are light and economical. Transparent plastic in particular – such as that used for the clear diffusing lens of a headlight – needs to be protected from UV radiation or else it becomes discoloured or brittle. This happens especially where materials are exposed to higher operating temperatures. Brand lamps are fitted with a special UV filter, meet the statutory requirements of ECE Standard R37 and guarantee that plastic headlights can be used without restrictions.

The UV filter symbol is displayed on the packaging. On the lamp itself, UV protection is guaranteed by a capital "U".

There is a lot of talk of daytime running light. What is to be gained by driving with low-beam lights on during the day?

Driving with lights during the day makes a major contribution to road safety. According to a study conducted for the EU by the Dutch Institute for Road Safety Research (SWOV), making daytime lighting obligatory would reduce serious multiple accidents with fatalities by up to 25% and cut collisions at intersections by as much as 35%.

Since 2011, new car models across Europe will have to be fitted with daytime running lights (DRLs). For older vehicles, there are numerous retrofit sets available – with long-life, optimised lamps for low-beam lighting or as high-comfort solutions with dedicated DRLs.

Can I use parking lights to make my vehicle more conspicuous during the day?

No, that is not an option. Parking lights are intended to enable other road users to recognise a parked automobile at night. Anyway, parking lights are not powerful enough to meet DRL safety requirements. The point here is to enable the road user to be recognised quickly during the day and in ambient light – and that calls for a certain brightness, which is provided by sophisticated high-performance DRL technology, or alternatively low-beam lights.

Incidentally, fog lights are not an option either. Across virtually the whole of the EU, it is against the law to drive with fog lights on during the day unless visibility is impaired.