Why Headlights Matter
Good headlights are a safety essential. Driving with a blown or dim headlight reduces your visibility of hazards ahead and makes your vehicle harder for oncoming traffic and pedestrians to see. In NZ, headlights must operate correctly to pass a Warrant of Fitness — a blown bulb or failed unit is an automatic fail.
Beyond compliance, modern LED headlights can illuminate road hazards significantly further than older halogen units, giving you more reaction time on unlit rural roads.
Types of Headlights
1. Halogen
The oldest and most common type in NZ's used import fleet. Halogen bulbs work like household incandescent bulbs but use a tungsten filament inside a halogen gas-filled envelope. They are:
- Cheap to replace ($10–$30 per bulb)
- Warm in colour (yellowish-white)
- Less energy efficient than modern alternatives
- Relatively dim compared to HID or LED
Many Toyota Corollas, Mazda Demios, and Honda Jazzes sold in NZ still use halogen headlights.
2. HID (High-Intensity Discharge) / Xenon
HID headlights create light by passing electricity through xenon gas rather than heating a filament. They are:
- Much brighter than halogen
- Blue-white in colour — the distinctive cool white look of 2000s–2010s premium cars
- Longer-lasting (2,000–3,000 hours vs 500–1,000 hours for halogen)
- More expensive to replace ($100–$300+ per bulb)
- Usually paired with auto-levelling systems (required to avoid blinding oncoming drivers)
Found on mid-spec Subaru Imprezas, some Mazda Atenzas, and various premium-brand JDM imports.
3. LED
LED headlights use arrays of light-emitting diodes. They are:
- Most energy efficient — generate much less heat for the light output
- Very long lifespan (often the life of the car)
- Bright and crisp white light
- Expensive to repair — individual LEDs are not usually replaceable; entire headlight units may need replacement, costing $400–$1,500+
Standard on newer cars — Toyota Yaris Cross, Mazda CX-5, Subaru Forester from 2019 onward.
What Causes Headlights to Dim or Fail?
Bulb Failure (Halogen and HID)
Most common cause. Halogen and HID bulbs have finite lifespans. Bulbs often fail suddenly, but can gradually dim as the filament or gas envelope ages. Replace both headlight bulbs at the same time — if one has failed, the other is likely close to end of life.
Cloudy or Yellowed Lens
UV radiation from sunlight causes the polycarbonate headlight lens to oxidise and turn yellow or milky. This reduces light output significantly. Headlight restoration (polishing and sealing the lens) can restore clarity for $50–$150 per pair at many NZ detailers or workshops. Severely oxidised lenses may need full headlight unit replacement.
Condensation Inside the Headlight Unit
Small amounts of condensation are normal and should clear after the headlight warms up. Persistent condensation — visible water droplets inside the lens — indicates a failed seal. Over time this corrodes the reflector and reduces output. Some units can be resealed; otherwise replacement is needed.
Blown Fuse
A blown headlight fuse will kill one or both headlights (depending on the circuit design). Check the fuse box before assuming a bulb or wiring fault.
Wiring or Relay Fault
Intermittent headlight failure — headlights that flicker or cut out at random — suggests a loose connector, corroded socket, or failed relay.
Headlights and the WoF
WoF inspectors check that:
- All headlights operate (low beam and high beam)
- Beam aim is within NZTA's approved angles (lights not aimed too high, dazzling oncoming drivers)
- Lenses are not cracked or broken
- No significant condensation or fogging
A headlight out, aimed incorrectly, or with a cracked lens is a WoF failure.
How Much Does Headlight Repair or Replacement Cost in NZ?
| Service | Estimated NZD Cost |
|---|---|
| Halogen bulb replacement (per bulb, parts + labour) | $30–$80 |
| HID bulb replacement | $120–$350 |
| Headlight restoration (polishing) | $60–$150 per pair |
| Headlight unit replacement (halogen, used) | $100–$300 |
| Headlight unit replacement (LED, new) | $400–$1,500+ |
| Beam alignment adjustment | $40–$80 |
When to Book a Mechanic
- Immediately if a headlight is out — driving at night is hazardous and it is a legal offence to drive without functioning headlights
- Before your WoF if lenses are cloudy or you suspect beam misalignment
- Promptly if headlights flicker or cut out intermittently — an intermittent fault may leave you without headlights at the worst possible moment