How to Check Your Car Lights Before Winter (and Avoid a £100 Fine)

• A two-minute walk-around check with a helper, plus a garage door test for headlight aim, catches the lighting faults that top the MOT failure list.
• Driving with a blown headlight can bring a fixed penalty of around £100 (about $134), rising to as much as £1,000 (about $1,340) if the case goes to court.
• Most bulbs cost from £3 (about $4) to buy, and a professional swap usually runs £15 to £100 (about $20 to $134), with bumper removal the main reason for the higher bills.

A Quick Lighting Check Before the Dark Evenings Arrive Can Save You an MOT Fail and a Roadside Fine

To check your car lights properly, park facing a wall or garage door, switch the ignition on, and ask someone to stand outside while you work through every switch: dipped beam, main beam, sidelights, front and rear fog lights, indicators on both sides, hazard lights, brake lights, reversing lights and the number plate light. Any lamp that is out, dim, flickering or a different colour from its partner needs a new bulb before you drive at night. Then look at the pattern the dipped beams throw on the wall. If one side sits clearly higher than the other, the aim is out, and that is the single most common reason cars fail the MOT.

The timing of the check is worth thinking about. The clocks go back on Sunday 25 October 2026, and from that week most commuters will drive home in the dark. A bulb that has been dead for months without you noticing suddenly becomes the difference between being seen and being missed, and it is also the kind of fault police officers pick up on the first dark evenings of autumn.

How to Run the Full Walk-Around Check in Five Minutes

The Driver and Vehicle Standards Agency (DVSA), which runs the MOT, gives owners a simple routine on its official blog for MOT testers. It suggests asking someone to sit in the car to operate the lamps while you walk around the outside, and it reminds drivers not to forget the hazard warning lamps and the number plate lights. Those two are easy to miss when you check on your own.

Work through it in this order so nothing gets skipped:

1. Front lights. Sidelights, then dipped beam, then main beam. Stand a few metres in front so you can compare the two sides. A yellowish, weak beam on one side often means that bulb is near the end of its life.
2. Indicators and hazards. Check left, right, then hazards. A fast flash on one side usually means a bulb has gone somewhere on that side, including the small repeater on the wing or mirror.
3. Brake lights. Your helper presses the brake pedal while you stand behind. On your own, reverse up to a window or garage door at night and watch the reflection.
4. Rear fog light and reversing lights. Select reverse with the engine off and the handbrake on (check your handbook first on automatics), then switch the fog light on and off.
5. Number plate light. This small lamp is an MOT item and is easy to forget.

While you are at the front, wipe the lenses. Rule 229 of the Highway Code says drivers must make sure lights are clean and number plates are clearly visible and legible before setting off in winter conditions. A film of road grime dulls the beam, and a clean cloth fixes it for free. If you see water droplets or mist trapped inside the lens, our guide on how to remove moisture from a car headlight covers the fix.

The Garage Door Test for Headlight Aim

DVSA says the top fail item for all vehicle types is “headlamp aim incorrectly set”, and it points owners who have had a headlamp or bulb replaced to a simple home check: shine the headlamps on a garage door or another suitable surface and see whether one is significantly higher than the other, or whether the aim looks too high or too low.

For the fairest result, park on level ground with normal tyre pressures and the boot empty, a few metres from a flat wall. On a UK car the dipped beam should have a flat top edge on the right-hand side and a step that kicks up to the left, so it lights the kerb without blinding oncoming drivers. If the two patches sit at clearly different heights, or the cut-off points up into the air, book a garage to set the aim with a beam setter. Many cars have a small headlamp levelling wheel on the dashboard, so check it is set to zero before you panic. A setting left on 3 or 4 from the last time you carried a heavy load will point both beams at the road just ahead of the bumper.

Why a Blown Bulb Can Cost You More Than the Bulb

The legal side is simple. Kwik Fit says a driver caught with a single working headlight can be handed a fixed penalty notice of around £100 (about $134), increasing up to £1,000 (about $1,340) if it goes to court. Officers also have discretion to issue a vehicle defect rectification notice instead, which gives the driver a set time to repair the fault and show proof. In some cases penalty points are possible, at the officer’s discretion.

The Highway Code also sets out when lights must be used, not just whether they work. Rule 226 says you must use headlights when visibility is seriously reduced, generally when you cannot see for more than 100 metres (328 feet). If one of those headlights is out, you are relying on half your intended output exactly when you need it most, and an oncoming driver can mistake a one-eyed car for a motorbike and misjudge its width.

Then there is the MOT. Headlamp aim is the top fail item on DVSA’s list, and a single blown bulb on test day is an avoidable fail. A few minutes with a helper the week before your test is the cheapest MOT preparation there is.

The darker months also bring a clear rise in risk. We covered the numbers behind the seasonal rise in collisions in our report on the crash rise when the clocks go back. Working lights will not fix tired drivers or wet roads, but they do make sure other road users can see you.

How to Change a Bulb Yourself and What a Garage Will Charge

On many older and mid-range cars a headlight bulb is a five-minute job with no tools. The usual steps are to open the bonnet, pull the rubber or plastic cover off the back of the headlamp unit, unclip the connector and the wire spring clip, lift the old bulb out, fit the new one with the tabs lined up, then refit the clip, connector and cover. Always switch the lights off first and let a recently used bulb cool.

Two things catch people out. First, buy the right bulb. Car headlight bulbs use an H code, with H1, H3, H4, H7, H11, HB3 and HB4 among the most common, and Bumper points out that none of them are interchangeable. The owner’s handbook lists every bulb the car uses. Second, do not touch the glass of a halogen bulb with bare fingers. Skin oils can make it fail early, so hold it by the metal base or wear clean gloves.

Costs are low for most cars. According to Bumper, bulbs can cost as little as £3 (about $4) from local car parts shops, and a professional replacement typically costs £15 to £100 (about $20 to $134). Halfords charges around £8 to £15 (about $11 to $20) for fitting, and often fits free when you buy the bulb in store. Labour is usually 15 to 30 minutes per bulb, which Bumper puts at £12 to £50 (about $16 to $67) at typical garage rates.

The expensive jobs are cars where the headlamp is buried. Some newer models need the front bumper or wheel arch liner removed to reach the back of the unit, and at that point a garage visit is sensible. If your car has sealed LED headlamps, a failed light usually means a new headlamp unit or LED module rather than a bulb, and that is a job to price with a dealer or specialist before you commit.

Upgrading to LED Bulbs

Aftermarket LED bulbs are sold widely as brighter replacements for halogen bulbs, and Bumper notes LEDs can last up to 30,000 hours. The catch is legality. Fitting LED bulbs into a headlamp designed for halogen can scatter light and blind other drivers, and it can affect your MOT. We explain the current position in what the MOT headlight rule means for drivers who fit aftermarket LED bulbs. If you want more light, a road-legal uprated halogen bulb of the correct type is the safer choice.

Edge Cases: When a Dead Light Is Not Just a Bulb

If a brand-new bulb does not light, the fault lies elsewhere. Check the fuse for that circuit first, using the fuse chart in the handbook or on the fuse box lid. A blown fuse costs pennies, but if it blows again straight away there is a short circuit that needs a garage.

If both brake lights are out at once, the likely cause is the brake light switch at the top of the pedal rather than two bulbs failing together. If a light flickers when you tap the lamp housing, suspect a corroded bulb holder or a loose connector. Rear lamp holders on hatchbacks are a common spot, as water gets in around the tailgate.

A dashboard bulb warning is also worth taking seriously. Many modern cars monitor the lighting circuits and flag a failed bulb on the instrument panel, but that system can miss a bulb that still works yet has dimmed badly with age. The walk-around check is still worth doing when the dashboard shows no warning at all.

Finally, if you drive a car with automatic headlights, do not assume they will come on in every condition that needs them. Automatic systems respond to light levels, and daytime running lights on some cars do not switch on the rear lamps at all. In fog, spray or heavy rain, switch to dipped beam manually so the tail lights come on too.

Sources

• DVSA MOT testing blog: Top 3 MOT fail items
• GOV.UK: The Highway Code, rules 226 to 237
• Kwik Fit: Is it illegal to drive with one headlight?
• Bumper: Headlight bulb replacement costs (UK prices)
• RAC Drive: How to change a car headlight bulb