MOT advisory explained
“Headlamp has a product on the lens”
The strangest wording on the certificate, and one of the most common. “A product on the lens” is the official phrase for a headlight that has gone yellow, cloudy or misted, and on some of the most reliable cars on the road it is close to guaranteed by fifteen years old.
The plastic lens on one or both headlamps has clouded, yellowed or crazed, or there is something on it, and the tester judged the beam still bright enough to pass. Older certificates say the same thing about the bulb or reflector inside.
5.0% fail on a headlamp at the next test and 22.9% are advised again. Clouding is a one-way process. The plastic is losing its clear coat, and each year of sun takes more of it.
Cloudy lenses cost you light long before they cost you an MOT. A badly yellowed lens can cut what reaches the road by half, and it scatters what is left into oncoming drivers’ eyes. The dashboard tells you nothing about it.
A “headlamp has a product on the lens but not seriously reducing light output” advisory means a headlamp lens has clouded, yellowed or crazed, or has a coating or deposit on it, but the beam is still bright enough to pass. The usual cause is sunlight on ageing plastic. According to DVSA MOT data analysed by PriceMyRepair, 5.0% of 1.2 million such advisories followed to the next test failed on a headlamp, and 22.9% were advised again.
What “a product” actually is
Sun damage. Nearly all modern headlamp lenses are polycarbonate with a thin ultraviolet-resistant coating. Once the coating wears through, the plastic underneath oxidises. It goes yellow first, then milky, then develops fine cracks. It happens fastest on the top of the lens, where the sun hits, and on cars that live outdoors.
Condensation. “condensation” is the one specific fault that shows up in the notes. A lamp that has lost its seal, or whose breather is blocked, mists up inside. The tester cannot wipe that away, so it is recorded here. It usually clears with the lamp on and comes back in the morning.
Failed repairs. Tinted films, sprayed clear coats and overspray from bodywork all land under this heading too. A tinted or smoked lens is a straight failure if it cuts the light noticeably. An amateur restoration that was polished but never recoated clouds again within months, and worse than before.
Will it fail next year?
3,789,584 of these advisories are on record, and 1,248,099 of them can be followed to the same car’s next MOT.
| What happened at the next test | Share |
|---|---|
| Failed on the same component | 5.0% |
| Same advisory recorded again | 22.9% |
According to DVSA MOT data analysed by PriceMyRepair: 1,248,099 advisories followed to the same vehicle’s next test. Rows can overlap.
For a fault that only gets worse it is a moderate figure, and the reason is the test. A lamp fails on light output only when the tester judges it seriously reduced, and cloudy plastic passes a surprising amount of light through. The lamp then fails on aim, because a scattered beam has no clear cut-off, and that shows up under a different wording.
Nearly a quarter are advised again. Lenses are not a thing people fix. They are a thing people stop noticing.
| Advisory wording | Fails on same part | Advised again | Followed |
|---|---|---|---|
| Direction indicator slightly discoloured | 6.1% | 19.6% | 1,901,107 |
| Stop lamp(s) non-obligatory stop lamp not working | 5.1% | 26.3% | 526,670 |
| Headlamp has a product on the lens | 5.0% | 22.9% | 1,248,099 |
| Position lamp slightly affected by the operation of another lamp | 3.9% | 12.7% | 121,142 |
| Registration plate deteriorated | 3.7% | 40.1% | 4,283,862 |
| Seat belt webbing slightly damaged or frayed | 3.1% | 23.6% | 1,047,800 |
| Brake pedal wearing smooth | 1.4% | 26.2% | 320,684 |
This advisory has a steep age curve. It is almost unknown below ten years, at 0.2 per 1,000 tests at 3–4 years, then multiplies to 16–19 years where it appears on one test in thirty. It falls again on the oldest cars, many of which have glass lenses that do not cloud. The failure rate climbs from 1.5% to 5.6% over the same span.
| Age of car | Per 1,000 tests | Fails on same part | Followed |
|---|---|---|---|
| 3–4 years | 0.2 | 1.5% | 6,092 |
| 5–6 years | 0.4 | 1.6% | 11,230 |
| 7–9 years | 1.2 | 1.9% | 47,350 |
| 10–12 years | 5.6 | 3.7% | 186,134 |
| 13–15 years | 18.8 | 5.3% | 444,382 |
| 16–19 years | 32.8 | 5.6% | 450,866 |
| 20 years and over | 22.5 | 5.3% | 98,113 |
A proper restoration sands the oxidised layer off, polishes the plastic clear, and then applies a new ultraviolet coating. The last step is the one that matters. Kits and detailers that skip it give you six clear months and then a lens that yellows faster than the original.
If the damage is inside the lamp, on the reflector or from condensation, polishing the outside does nothing and a new unit is the answer. Lamps for common cars are often cheaper than people expect from a pattern supplier.
After any lens work, have the headlamp aim checked. Removing a lamp to restore it, or fitting a new one, usually knocks the aim out, and aim is the most common headlamp failure in the MOT.
Exact wording on your certificate
Two wordings, one for the lens and one for the light source inside. The failure is the same sentence with the opposite conclusion.
| Line on the certificate | Result | Code |
|---|---|---|
| Headlamp has a product on the lens but not seriously reducing light output | Advisory — pass | 4.1.4 (b) |
| Headlamp has a product on the light source but not seriously reducing light output | Advisory — pass | 4.1.4 (b) |
| Headlamp has a product on the lens or light source that obviously reduces light output | Major — fail | 4.1.4 (b) |
Left and right are level, and testers write “both” more often than anything else. The sun does not favour a side, and both lenses left the factory on the same day.
| Position written by the tester | Share of all instances |
|---|---|
| Offside front | 19% |
| Nearside front | 19% |
| Front | 17% |
| Offside | 16% |
| Nearside | 16% |
| No position recorded | 12% |
From 3,789,584 recorded instances. Testers can add their own note after the standard wording. The most common on this advisory: “both” (288,688), “both sides” (157,548), “both side” (39,936), “both front” (37,057), “nearside and offside” (20,046), “both headlamps” (11,760), “n/s and o/s” (10,205), “both fronts” (9,245).
What it costs
A professional lens restoration with a new coating is a fixed labour job, and a good one costs a fraction of a new lamp. Replacement headlamp units range from modest, for a pattern part on a common hatchback, to a great deal for a lamp with LED or adaptive lighting built in. The spread is too wide for one honest range, so ask with your registration. Other prices are on the repair costs index.
Can I still drive with this advisory?
Be aware that you have less light at night than the car was designed to give, and that oncoming drivers may be dazzled by the scatter. Sort it before the clocks go back rather than before the next MOT.
Enter your reg to see every headlamp advisory on your car, and whether aim has been flagged alongside the lens.
Which cars get this advisory most?
The all-vehicle rate is 7.2 per 1,000 tests. On the models below it is three to five times that.
| Model | Per 1,000 tests | Vs all cars | Tests |
|---|---|---|---|
| Toyota Corolla | 39 | 5.3× | 1,166,652 |
| Honda Jazz | 30 | 4.1× | 3,292,357 |
| Ford Fusion | 29 | 4.0× | 717,369 |
| Toyota Yaris | 27 | 3.7× | 4,619,042 |
| Honda Civic | 26 | 3.6× | 3,259,563 |
| Toyota Prius | 24 | 3.3× | 1,441,205 |
| Mazda 2 | 22 | 3.0× | 1,269,505 |
| Honda CR-V | 22 | 3.0× | 2,048,932 |
| Nissan Micra | 21 | 2.9× | 2,941,349 |
| Mitsubishi Shogun | 21 | 2.9× | 420,039 |
Model families are grouped by the first word of the DVSA model name, so “Transit” covers every Transit variant. Only models with at least 60,000 tests are ranked.
This is a list of cars that outlive their headlights. The Toyota Corolla at 5.3 times the average, then the Honda Jazz, Toyota Yaris, Honda Civic, Toyota Prius and Honda CR-V: Toyota and Honda take six of the ten places. Nothing is wrong with their lamps. They are simply still being tested at an age when most other cars have been scrapped, and polycarbonate has a lifespan.
If you own one, budget for the lenses the way you would for tyres. It is a wear item on a car this long-lived.
What to do next
- Look at the lens in daylight. Yellow or milky on the outside is sun damage and can be restored. Misting or dirt on the inside means the lamp itself.
- Have it restored with a coating, or replace it. Ask specifically whether a new ultraviolet coat is applied. If the answer is vague, go elsewhere.
- Do both. They are the same age and one clear lens beside one cloudy one looks worse than two cloudy ones.
- Get the aim checked afterwards. Any garage with a beam setter will do it in minutes, and it is the failure that follows lens work.
Headlamp product on the lens FAQ
What does headlamp has a product on the lens mean on an MOT?
It is the official wording for a headlamp lens that is clouded, yellowed, crazed, or has a coating or deposit on it, while the beam is still bright enough to pass. It is an advisory.
Will cloudy headlights fail the MOT?
They fail when the tester judges that the clouding obviously reduces the light output, or when the scattered beam fails the aim check. According to DVSA MOT data analysed by PriceMyRepair, 5.0% of 1.2 million such advisories failed on a headlamp at the next test.
Can cloudy headlight lenses be restored?
Yes, if the damage is on the outside. The oxidised layer is sanded and polished off and a new ultraviolet coating is applied. Without the coating the lens will cloud again within months.
How much does it cost to fix cloudy headlights?
A professional restoration is a fixed labour job. A replacement headlamp ranges from a modest pattern part to a costly unit with LED or adaptive lighting. Any prices we publish are estimates and final quotes come from garages.
Why do headlights go yellow?
Sunlight. The polycarbonate lens has a thin ultraviolet coating, and once that wears through the plastic oxidises and yellows. Cars kept outdoors, and long-lived cars, are affected most.
Which cars get this advisory most?
Long-lived ones. The Toyota Corolla, Honda Jazz and Ford Fusion lead, and Toyota and Honda models take six of the top ten places, because they are still being tested at ages most cars never reach.
How these figures were calculated. According to DVSA MOT data analysed by PriceMyRepair, from the DVSA anonymised MOT test results (Open Government Licence v3.0): 350,943,111 tests. This advisory was recorded 3,789,584 times; 1,248,099 of those were followed to the same vehicle’s next test between 180 and 730 days later. “Fails on the same part” means a failure at that next test under the same defect code and naming the same component, on either side of the vehicle. Testers do not always name a component the same way twice, so the figure is a floor. Method and how to cite.