Lighting / BUYING GUIDE
Halogen, xenon HID and LED headlights: choose for your existing system
Start with the headlamp already fitted to your car. Bulb technology, connectors and the headlamp optics work together; a brighter-sounding specification does not establish compatibility.
Read the original bulb marking and check whether the headlamp uses halogen, xenon HID or factory LED technology. Keep the fitting code and the system type separate when comparing replacements.
How the three systems differ
| System | Light source | What to check |
|---|---|---|
| Halogen | A heated filament in the bulb. | The specified bulb type, wattage and headlamp application. |
| Xenon HID | An electric arc in a discharge lamp, powered through a compatible ballast. | The complete D-series fitting, connector and existing ballast system. |
| LED | Light-emitting diodes with their associated electronics. | The precise application, electronics, cooling clearance and product restrictions. |
D1S HID versus D1S LED
These describe different technologies even when the advertised fitting name starts with D1S. A matching code does not by itself confirm that an LED replacement will work with your ballast, fit behind the dust cover or suit the headlamp optics. Compare the installation details and read the individual product notice. TTRP LED headlight replacements carry off-road-use restrictions; they are not advertised as universally approved road conversions.
D1S, D2S, D3S and D4S are different fittings
Match every character of the original bulb code. Do not choose by colour temperature or vehicle badge alone: the same model can have different headlamp options. Our D1S versus D3S guide explains the fitting checks for those two types.
Judge the complete light pattern
Lumen figures describe light output; they do not tell you exactly where that light lands on the road. Headlamp optics and adjustment matter. A cool-white colour description is not proof of a better beam or of compatibility.
Four checks before ordering
- Identify the original bulb marking and headlamp version.
- Match the connector, ballast or driver requirements.
- Check physical clearance, cooling and the product's stated use restrictions.
- If uncertain, send your vehicle details and a photo of the original label through our fitment-help page.
For HID systems, fitting by a qualified technician is recommended because the system uses high voltage. Replacing a worn bulb does not resolve damaged optics, wiring or a faulty ballast.
Sources & product references
Technical guidance checked against the references below. Vehicle fitment still requires an exact part check.