What Constitutes a DRL MOT Failure?
Daytime Running Lights (DRLs) are increasingly common on modern vehicles, designed to improve visibility during daylight hours. However, despite their safety intent, they are a frequent cause of a vehicle failing its MOT test. A DRL MOT failure occurs when these lights do not meet the stringent requirements set out in the MOT test guidelines regarding their function, condition, or fitting. This isn't just about whether they light up; it encompasses their brightness, colour, positioning, and whether they operate correctly in conjunction with other lighting systems.
- DRLs must function correctly to pass an MOT.
- Incorrect brightness or colour is a common failure point.
- Faulty DRL wiring or control units lead to failure.
- Mandatory DRLs must operate as intended.
The MOT test, overseen by the Driver and Vehicle Standards Agency (DVSA), aims to ensure all vehicles on the road are safe and compliant. Lighting is a critical component of this. For vehicles where DRLs are fitted as standard equipment, their presence means they are inspected. If they are not working, are damaged, or are incorrectly fitted, they will be logged as a defect. This can range from a simple advisory note, highlighting a potential issue that might worsen, to a full failure, necessitating immediate repair before the vehicle can pass its test and receive its MOT certificate. For many, the surprise DRL MOT failure can be frustrating, especially if they were unaware of any issues.
DRL Functionality and the MOT Test
The primary reason for DRLs to cause an MOT failure is their basic functionality. The MOT test guidelines stipulate that all lights fitted to a vehicle must be in good working order. For DRLs, this means they must illuminate when the engine is running and other lights (like dipped or main beams) are not activated. They should also extinguish or dim when the headlights are turned on, unless they are designed to remain on at a lower intensity as part of the main lighting system, which is rare for typical DRLs. A bulb that is out, flickering, or completely non-operational will result in a fail. The tester will check each DRL unit individually.
Condition and Damage as a Failure Point
Beyond simply illuminating, the physical condition of the DRL units is also scrutinised. Cracked or broken lenses, significant corrosion within the unit, or loose fittings are all grounds for an MOT failure. The DVSA's MOT inspection manual details that lighting equipment must be in good condition, free from significant damage that could affect its performance or emit glare. Even if the light itself works perfectly, a shattered lens might allow moisture ingress, leading to future failure, or scatter light in an uncontrolled way. These visible defects are often picked up during the visual inspection part of the MOT test.
Common Causes of DRL MOT Failure
When your vehicle undergoes its MOT test, the inspector checks for specific faults that could compromise road safety. For Daytime Running Lights, several recurring issues frequently lead to a DRL MOT failure, often stemming from simple wear and tear or installation errors. Understanding these common pitfalls can help you proactively address them before your test.
Bulb Failures and LED Issues
Many DRLs use LED technology, which is generally long-lasting, but not infallible. A single LED within a cluster can fail, causing the light to appear dimmer or to have dark spots. In some cases, the entire DRL unit may cease to function. For vehicles still using traditional bulbs for DRLs, blown bulbs are a straightforward MOT failure. The MOT test guidelines require all fitted lights to be operational. If one or both DRLs are out, it's an immediate fail. Even if the DRLs are part of a complex integrated unit, a failure in the DRL circuit will be flagged. This is often the most direct cause for a DRL MOT failure.
Wiring and Electrical Faults
The electrical system powering the DRLs can also be a source of failure. Corroded wiring, loose connections, or faults within the DRL control module (if fitted) can lead to intermittent operation or complete failure. A DRL MOT failure due to wiring might manifest as one light working and the other not, or lights flickering. Testers will look for exposed or damaged wiring, which itself can be a fail item due to the risk of short circuits or chafing. Modern vehicles often have sophisticated electronics, and a fault in the DRL circuit can trigger warning lights or system errors that an MOT tester will note.
Incorrect Brightness or Colour
DRLs are designed to be bright enough to be seen easily during the day, but not so bright as to cause glare or be confused with other lights, such as indicators or fog lights. The MOT test guidelines specify that DRLs must emit a white or amber light, and their intensity must be appropriate. If DRLs are excessively bright, they can fail the test by causing discomfort to other road users. Conversely, if they are too dim to be effective, they can also result in a fail. Some aftermarket DRLs, or modifications to standard units, might emit colours outside the approved range (e.g., blue or red), which is an immediate fail. The specific brightness and colour requirements are detailed within the official MOT test guidelines.
Mounting and Fitment Issues
The way DRLs are fitted to the vehicle is also checked. They must be securely mounted, pointing straight ahead, and positioned correctly according to manufacturer specifications or regulatory requirements. If DRLs are loose, hanging precariously, or have been fitted at an angle that creates undue glare or is not symmetrical with the other DRL, this can lead to a DRL MOT failure. Any modification that affects the original fitment, such as poorly installed aftermarket DRL strips, needs to be done to a professional standard to avoid issues during the MOT test.
Preventing a DRL MOT Failure
Avoiding a DRL MOT failure often comes down to vigilance and understanding what the MOT test inspectors are looking for. By taking a few simple steps, you can significantly increase the chances of your daytime running lights passing inspection without issue.
Before your MOT is due, take a moment to walk around your car with the engine running and the main lights off. Check that both DRLs are illuminated, appear to be the same brightness, and are a consistent white or amber colour. This quick check can highlight obvious issues.
Regular Vehicle Maintenance
The best defence against a DRL MOT failure is regular vehicle maintenance. This includes periodically checking your lights, not just before the MOT. If you notice a DRL is out, flickering, or damaged, get it repaired promptly. For vehicles where DRLs are integrated into complex headlight units, it might be worth having an auto electrician or garage check the entire lighting system during routine servicing. They can identify potential problems with wiring or control modules before they become critical failures during the MOT test. This proactive approach is key to avoiding an unexpected DRL MOT failure.
Checking DRLs in an Electric Car MOT
The rules for an electric car MOT are largely the same as for internal combustion engine vehicles, including checks on lighting. While electric cars may have advanced lighting systems, the fundamental requirements for DRLs remain. Electric car MOT failures related to DRLs will stem from the same issues: non-functioning units, damage, incorrect brightness or colour, or electrical faults. The underlying technology might differ, but the test criteria for visibility and safety are consistent. If you have an electric car, ensure its DRLs are functioning correctly as part of your routine checks to prevent an electric car MOT failure.
What Happens After a DRL Failure?
If your vehicle fails its MOT due to DRL issues, the tester will provide a VT30 refusal of an MOT test certificate, detailing the defects. For a DRL MOT failure, the specific lighting faults will be listed. You will then need to have the necessary repairs carried out. Depending on the severity, the repairs might be minor, such as replacing a bulb or fixing a loose connection. In other cases, it might involve replacing an entire DRL unit or rectifying complex wiring problems. Once repairs are complete, you will typically need to take your vehicle for a partial retest, which often focuses solely on the failed items. If all the defects are rectified, your vehicle will pass the MOT test.
The most common DRL MOT failures arise from simple issues like blown bulbs, wiring faults, or incorrect colouration, all of which are preventable with regular checks.
Understanding MOT Advisory Notices
Sometimes, a DRL might not be completely failed but will be noted as an 'advisory' on the MOT test certificate. This means the light is currently working but has a minor issue that could potentially lead to a failure in the future. Examples include a DRL lens that is slightly cloudy, minor corrosion on a connector, or a DRL that is just on the borderline for brightness. While an advisory isn't a fail, it's a warning. It's wise to address advisory items, especially concerning lights, as they can develop into full MOT failure points by the time your next MOT test is due.
DRL Regulations and Your MOT
The regulations surrounding vehicle lighting, including Daytime Running Lights, are designed to ensure all vehicles are visible and safe on the road. Understanding these regulations is key to comprehending why a DRL MOT failure might occur and how to avoid it.
When Will a New Car Need Its First MOT Test?
A common question for new car owners is when their vehicle will first require an MOT. Generally, a new car will not need its first MOT test until it is three years old. This period allows for the assumption that a relatively new vehicle is in good mechanical condition. However, this exemption applies only to the initial test; after three years, the vehicle is subject to the annual MOT test, and all components, including DRLs, must comply with the MOT test guidelines. If DRLs are fitted as standard, they will be inspected from the first MOT onwards.
DRLs as Part of the MOT Test Guidelines
The MOT test guidelines are precise about vehicle lighting. For DRLs, they must be fitted symmetrically, on the front of the vehicle, and emit white light. Amber DRLs are permissible in certain circumstances or on specific vehicle types as defined by legislation, but white is the most common. Crucially, they must be operational and in good condition. If DRLs are not fitted as standard equipment on a vehicle, they are not tested. However, if they were factory-fitted or have been added as an upgrade and are connected to the vehicle's electrical system, they become subject to inspection. A DRL MOT failure will occur if these lights do not meet the defined standards for visibility, colour, and condition.
DRL MOT Failure List and Common Issues
The MOT failure list is extensive, and lighting defects, including those related to DRLs, appear frequently. Common issues leading to a DRL MOT failure include:
- Bulbs that are out or not illuminated.
- LED units that have failed or have visible dark spots.
- Cracked, damaged, or insecurely mounted DRL lenses or units.
- Wiring issues causing intermittent light or no light at all.
- DRLs emitting a colour other than white (or approved amber).
- DRLs that are excessively bright or dim.
- Aftermarket DRLs that are poorly installed or do not meet standards.
These points highlight that the MOT test is thorough, looking at both the function and the integrity of the DRL system. Many of these are preventable with basic upkeep and awareness.