LED Headlight Buying Guide
Swapping halogen headlights for LED should double your night vision — yet many buyers end up with glare tickets, flickering dashboards or bulbs that die in a year. This guide covers fitment codes, CANbus compatibility, beam cutoff and the specs that actually matter.
Quick-Reference Specs
| Parameter | What to look for |
|---|---|
| Common fitments | H4 / H7 / 9005 (HB3) / 9006 (HB4) / H11 / H8 / H9 / H13 / 9012 |
| Color temperature | 5000K–6000K recommended (white, maximum retinal sensitivity) |
| Per-bulb output | 6,000–12,000 effective lumens per pair for quality units |
| CANbus | Built-in decoders required for most European & late-model US vehicles |
| Cooling | Copper braided belt or micro-fan; both work if the housing has airflow |
| Voltage | 9–16V with over/under-voltage protection |
| Lifespan | 30,000–50,000 hours (vs ~1,000 h for halogen) |
Step 1: identify your bulb fitment before anything else
Check the owner's manual or remove the existing bulb — the base code (H4, 9005, H11…) is printed on it. An LED "conversion" must use the same base geometry to lock into the housing correctly.
H4 (also called 9003/HB2) is a dual-filament base used in many older cars, motorcycles and trucks — choose LED bulbs with dual-beam chips that replicate high/low function.
Step 2: beam cutoff is what separates a good bulb from a dangerous one
A halogen reflector or projector is designed around a filament at one precise point. An LED bulb places its chips in different positions, which can scatter light above the cutoff line and blind oncoming traffic.
Look for bulbs where the LED chips are arranged to mimic the filament position — a 1:1 filament design. Aurora headlight bulbs are photometrically verified to preserve the cutoff line (ECE R48 chromaticity and beam-pattern scans are in the Optical Scanning library).
After installation, aim the headlights against a wall: the low-beam cutoff should sit at or slightly below headlight height at 7.6 m.
Step 3: CANbus — why your dashboard hates cheap LEDs
Modern vehicles monitor bulb resistance. LEDs draw so little current that the car flags a "bulb out" error or strobes the light. Bulbs with built-in CANbus decoders mimic halogen load and prevent this.
European brands (VW, BMW, Mercedes, Audi) and many late-model US vehicles require decoders. Some vehicles also need pulse-width modulation filtering for fog-light positions.
Step 4: color temperature and real brightness
5000K–6000K delivers the best balance of perceived brightness and wet-road performance. 8000K+ blue bulbs reduce usable light despite looking "brighter" — avoid them.
Trust effective lumens measured at the lens, and beware of 20,000-lumen claims on fanless mini bulbs — physics limits how much heat a compact body can shed.
Step 5: cooling design predicts lifespan
Micro-fan bulbs cool better in enclosed projectors; copper-braid bulbs are quieter and more vibration-proof in motorbikes and machinery. Both fail early if the housing is fully sealed with no air path — check your housing type.
Frequently Asked Questions
Are LED headlight bulbs street legal?
Regulations differ by market. In most regions, LEDs are legal for off-road and auxiliary use, while road-legality depends on the housing and beam certification. For street-driven vehicles, verify local rules and choose bulbs with verified beam patterns that preserve the cutoff.
Why do my new LED bulbs flicker?
Almost always CANbus: the car pulses power to check the bulb. Use bulbs with integrated decoders, or add external CANbus modules. Flicker can also come from poor grounding.
Do I need to replace both bulbs at once?
Yes — LED chips age together, and mismatched bulbs create uneven beams. Buy pairs from the same production batch.
Can I use LED bulbs in projector housings designed for halogen?
Only with bulbs whose chip position matches the projector focal point; otherwise output scatters inside the projector and distance drops. Check optical scan data before buying.
Need help specifying your lighting?
Our engineers answer technical questions within 24 hours. OEM/ODM projects start from 100 pcs with IATF 16949 certified processes.