MOT Light Checks: Avoid Failure

Don't Let Your Lights Dim Your MOT Hopes

The MOT test is a crucial annual event for every car owner in the UK. It ensures your vehicle meets minimum safety and environmental standards. While many drivers focus on the engine, brakes, and tyres, a surprisingly common reason for MOT failure lies in something far simpler: your car's lights. Faulty or incorrect exterior lighting can lead to a failed test, resulting in inconvenience and unexpected costs. This guide will walk you through everything you need to know about checking your car's lights before your MOT, helping you avoid a dreaded failure notice.

Why Lights are a Major MOT Hurdle

It's a startling statistic, but a significant percentage of vehicles fail their MOT due to issues with their exterior lights. This isn't just about a bulb being out; it encompasses a range of potential problems. The testers are rigorously trained to check not only that lights are functioning but also that they are the correct colour, brightness, and are properly positioned. Any obstruction, damage that affects performance, or incorrect fittings can lead to a fail. Importantly, this refers to the exterior lights of your vehicle, not the numerous dashboard warning lights which are now subject to separate, and equally important, checks.

DIY Light Checks: A Simple Pre-MOT Routine

The good news is that checking your car's lights is a relatively straightforward task that you can perform yourself with minimal fuss. A quick inspection before you book your MOT can save you a lot of hassle. Here’s how to approach it:

1. Visibility and Obstructions

Before anything else, ensure that all your lights are clearly visible. If you've recently fitted any accessories, such as a bull bar, driving lamps, or even decorative covers, check that they do not obscure any of the required lights. Any fitting that covers or partially covers a light unit is a potential MOT failure. Keep your light lenses clean and free from excessive dirt or grime, as this can also affect their visibility and the intensity of the light emitted.

2. Functionality and Bulb Replacement

The most common issue is a blown bulb. You'll need a helper for this, or you can use reflections in a wall or shop window. Systematically go through each light and ensure it illuminates when activated. For bulb replacement, you can purchase spares from most auto shops or even petrol stations. The ease of changing a bulb varies dramatically between car models. Some vehicles offer easy access to the light clusters, allowing for a quick swap. Others, however, are notoriously tricky, requiring contortions and a good deal of patience to access the bulbs, dealing with fiddly clips and clasps. If you're not comfortable with this, it's often best to leave it to the professionals.

3. Colour and Brightness

Lights must emit the correct colour of light. For instance, front lights should be white, and rear lights red. Indicators must be amber. If you're replacing a bulb, ensure you get the correct type and colour. Sometimes, indicator bulbs have an orange coating that can degrade over time, turning the light white instead of amber – this will cause a fail.

Detailed Breakdown of Each Light Type

To help you conduct a thorough check, here’s a detailed look at each type of exterior light and what the MOT testers will be looking for:

Troubleshooting Common Light Issues

When an individual light fails, it's often down to a simple bulb issue or some minor corrosion within the light cluster that can be cleaned. If you find that a group of lights aren't working, this could indicate a blown fuse. Fuses are inexpensive and relatively easy to replace, usually found in a fuse box under the dashboard or bonnet. If it's not a fuse, the problem might lie with relays or more complex electrical wiring issues, which would require a mechanic's expertise.

Headlight Aim and Alignment

While not strictly a 'light not working' issue, the aim and alignment of your headlights are critical for an MOT. Headlights must illuminate the road ahead effectively without dazzling oncoming drivers. Most modern cars have adjustable headlights, and this is usually a simple adjustment that a garage can perform. While cracked lenses are often acceptable, if the crack is severe enough to affect the light's pattern or spread, or if it allows water ingress, it will be a fail. Using lens repair tape can be a temporary fix to prevent water from entering, but a permanent repair or replacement might be necessary.

Indicator Speed and Dashboard Lights

The flashing frequency of your indicators is tested. If they flash too slowly (or too quickly), they can be deemed ineffective and cause a fail. This is often referred to as 'lazy' indicators. Similarly, if your vehicle has a dashboard indicator warning light (which most do), this must also function correctly to show you when your indicators are active. This is particularly important for hazard lights, which require both the indicator lights and the dashboard warning light to operate correctly.

When to Call in the Professionals

While many light issues can be resolved with a simple bulb change or fuse replacement, some problems may require more specialised knowledge and tools. If you're unsure about how to access a particular bulb, diagnose an electrical fault, or adjust headlight aim, it's always best to consult a qualified mechanic. Garages like Triggs Garage in Hutton, near Brentwood, Essex, are equipped to handle all your vehicle servicing and MOT needs, ensuring your car is roadworthy and compliant with all regulations.

Frequently Asked Questions

Q1: What happens if my car's lights are dirty for the MOT?
While excessive dirt obscuring the light can cause a fail, a light coating of road grime is usually acceptable. However, it's always best to clean your lights before the test for optimal visibility.

Q2: Can I use coloured bulbs in my car?
No, you must use the correct colour bulbs. Front lights should be white, rear lights red, and indicators amber. Any deviation will result in a fail.

Q3: My headlight has a crack, will it fail the MOT?
Minor cracks in headlight lenses are usually acceptable as long as they do not affect the light output, pattern, or strength, and do not allow water ingress. However, significant damage or damage that compromises the light's function will cause a fail.

Q4: What if only one of my rear fog lights works?
If your car is fitted with only one rear fog light as standard (often on the passenger side), then it only needs that one to work correctly. If your car has two and only one works, it will fail.

Q5: How can I check my brake lights without a helper?
You can check your brake lights by parking your car facing a wall or reflective surface. When you press the brake pedal, you should see the reflection of the illuminated brake lights.

By taking a little time to check your car's lights before your MOT, you can significantly increase your chances of passing first time, saving you time, money, and the stress of a failed test. A little preparation goes a long way in ensuring your vehicle is safe and compliant.

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