That yellow veil probably is not dirt. It is usually the sun-damaged surface of the lens, which is why another energetic wash changes almost nothing.
Wash the lamps first, then restore oxidised outer lenses with progressively finer abrasives and polish. The crucial final job is a UV-protective seal: without it, you have removed the damaged factory coating and left the polycarbonate exposed again.
First decide what sort of cloudiness you have
Cloudiness has three quite different causes, and only one calls for sandpaper. Ordinary road film sits on the outside and should wash off. Oxidation also affects the outside, but the RAC explains that the clear coating wears away over time and UV light then oxidises the casing, turning it yellow. Moisture, meanwhile, can collect inside the lamp.
That diagnosis matters. Abrading a dirty but sound lens wastes its protective coating; polishing the outside of a lamp with an internal leak fixes nothing.
It was surface contamination. Keep the lamps clean and stop there.
The outer coating has probably oxidised. Restore the lens, then add UV protection.
Turn the lamps on and see whether light misting clears. Persistent moisture points to blocked vents or failed seals.
Modern headlamps are ventilated rather than airtight. HELLA says some misting is normal if it clears with the lights on; persistent fog calls for checks to the seals and ventilation slots. Condensation is more common in colder months, and LED or xenon units can take longer to clear than halogen lamps because they produce less heat.
This scale is an editorial guide to choosing a treatment, not a measured severity score.
How to clean cloudy headlights properly
The sound method is clean, mask, abrade, refine, polish and protect. Follow the sequence supplied with your chosen product rather than mixing instructions from several kits: Autoglym uses P800, P1500, P2000 and P3000 discs before compound, while the RAC’s hand-sanding sequence runs from 400 through 600 and 1000 to 2000 grit.
- Wash both lenses. Remove road film first so you can see whether restoration is required, as Halfords advises in its cleaning guide.
- Inspect inside and out. External yellowing calls for restoration; internal mist needs the ventilation and seals checked instead.
- Mask around each lamp. Autoglym includes masking as a distinct step before sanding, protecting the surrounding area while you work.
- Abrade in the specified sequence. Start with the kit's first grade and progress through every finer grade. Do not improvise a grit order.
- Refine and polish. The finer discs remove the marks left by the coarser stage; compound then restores clarity.
- Apply UV protection. Use the supplied sealing wipe or coating exactly as directed. If the kit supplies none, buy a compatible protective finish rather than leaving freshly polished polycarbonate bare.
- Treat the pair. Restore both sides so their colour and intensity remain substantially matched.
That omission is not trivia. Sanding removes the original protective layer. A coatings supplier, Resin Pro, describes a fresh 2K clear coat as a replacement sacrificial layer that shields the polycarbonate from UV. The RAC gives the less specialised option of finishing with wax as a protective layer.
Do
- Wash before deciding to sand
- Follow one complete abrasive sequence
- Restore the lamps as a pair
- Finish with UV protection
Don't
- Treat internal condensation as outer haze
- Jump randomly between grit grades
- Assume polish alone is the finish
- Expect toothpaste to make a lasting repair
The kit prices hide one important difference
The cheapest route begins at £8.99, but price alone does not tell you whether a product will tackle serious oxidation or protect the result. Read the process and contents. A cleaner intended for light oxidation is not the same proposition as a multi-grade sanding kit.
| Product | Process and protection | Price checked 23 October 2026 |
|---|---|---|
| Armor All Restorer Wipes | Chemical treatment and sealing wipe; claimed 10-minute application, then about 3 hours to become touch-dry | £8.99 |
| Turtle Wax Cleaner & Sealant | Single-step liquid for light oxidation | £9.99 |
| Turtle Wax Speed Restorer | Compound, pad and two ceramic sealing wipes | £17.99 |
| Cerakote Ceramic kit | Wipes, four sanding discs and ceramic wipes; manufacturer claims a 30-minute process | £24.95 ex VAT, about £29.94 inc VAT |
| Autoglym Complete kit | P800 to P3000 discs and compound; no sealant | £30 at Halfords; £34.49 direct |
| Meguiar’s Ultimate kit | 1000 and 3000 grit discs plus two sealant wipes; no power tool | £38.40 |
The professional option starts above the DIY products listed here, but it can make sense when you do not want to abrade a costly lamp by trial and error. For context, the RAC gives a halogen bulb from £9 but a VW Polo LED headlight unit at £846. Those are different components, yet they show why “headlight cost” can mean anything from pocket money to a painful invoice.
DIY kit
- Listed options from £8.99
- Sealant is included in several kits
- Hand-use choices need no power tool
- Some kits omit UV protection
- You must follow the abrasive sequence
- Durability claims lack an independent UK comparison
Professional restoration
- Published services offer sanding, polishing and UV coating
- One £45-a-pair service includes a 1-year warranty
- Avoids learning on an expensive lamp
- Published pair prices range from £45 to £70, with another service from £85
- Travel can cost extra
- Price depends on vehicle and condition
There is no independent UK comparison showing how long each restored finish stays clear. The claims span “over 12 months” for a Meguiar’s product mentioned by the RAC, a limited lifetime warranty from Cerakote, and a 1-year warranty from one mobile specialist. Treat each as the maker’s or seller’s promise, not a universal lifespan.
Cloudiness is not an automatic MOT failure
In Great Britain, the MOT decision is a gradient. The DVSA inspection manual grades a slightly defective headlamp lens as Minor and a seriously defective or missing lens as Major. An obviously incorrect beam image or aim outside the permitted limits is also Major.
The tester judges what the lens does to output, colour and beam pattern; there is no magic haze percentage. The same manual says lamps forming a matched pair should have substantially the same colour and intensity, and the same size and shape. That is a practical reason to restore both, even if one faces the sun more often.
A GB tester cannot carry out repairs during the MOT, although minor aim adjustment is allowed. Restore beforehand, and consider an alignment check if parts have been removed. Halfords lists alignment for both lamps from £20, while HELLA warns that removing headlamp parts can disturb the aim.
Toothpaste improves appearances, not the underlying job
Toothpaste can make a visible difference because it polishes. That does not turn it into a complete restoration system. Auto Express tried Colgate on a badly weathered Astra lens in 2019 and saw a visible improvement after plenty of rubbing, but judged the finish imperfect. The RAC groups toothpaste, baking soda, vinegar, cola and hand-sanding home remedies as temporary measures rather than long-term fixes.
The missing stage is protection. If a treatment merely makes the surface shinier but neither removes the failed layer consistently nor replaces its UV defence, the lens remains vulnerable. WD-40 has no endorsement here from a UK motoring body or headlamp-kit maker, so it is not a substitute for a system designed to restore and seal a lens.
Parking in shade can reduce UV exposure, according to the RAC. The direction a car habitually faces can matter too: one lamp may spend far longer in direct sun, leaving the pair visibly uneven. Our guide explains how often to wash your car in the UK; for the washing stage itself, see how to use a jet wash. You can also find a nearby car wash when doing it at home is inconvenient.
Wash first and diagnose the right problem. For external yellowing, choose a complete restoration process and value the UV sealant more than a flashy disc count. Work on both lamps, finish the protection properly and deal with persistent internal moisture or poor beam aim as separate faults.
Figures and retail prices were checked on 23 October 2026; the DVSA manual was updated on 14 October 2026.