---
title: "DRL MOT Failure: Why Running Lights Fail and How It's Fixed"
description: "DRL MOT failure explained: which cars have their daytime running lights tested, how a dead or yellowed DRL is graded, and how the unit is put right."
url: https://headlightrepairshop.co.uk/guides/drl-mot-failure/
lang: en-GB
---

# DRL MOT Failure: Why Running Lights Fail and How It's Fixed

A DRL MOT failure only applies to some cars, and not every running light fault is a fail. Whether yours counts depends on the date the car was first used and on how the light has gone wrong: out, dim, flickering or brown. This guide covers what the tester looks at, why the lights go, and the repair.

[Get a quote](https://headlightrepairshop.co.uk/get-a-quote/) [How it works](https://headlightrepairshop.co.uk/how-it-works/)

![Car waiting in the rain at the open door of a test bay, one running light white and the other dark](https://headlightrepairshop.co.uk/img/guides_drl-mot-failure.webp)

## Which cars have their running lights tested

The MOT inspection manual only asks for daytime running lamps to be inspected when they were fitted as original equipment to a car first used on or after 1 March 2018. The V5C logbook shows the date of first registration, which is the place to start.

The manual also lets a DRL do the job of the front position light, and position lights are checked on cars of any age. On an older car whose running light doubles as the sidelight, a fault can still come up at the test.

Where it is tested, the DRL must come on and go off with the engine. It may dim or switch off with the headlamps, or on the side where the indicator is flashing.

![Running lights reflected in a puddle, one white and one amber: the fault behind a DRL MOT failure](https://headlightrepairshop.co.uk/img/guides_drl-mot-failure_running-lights-reflection.webp)

## How a running light fault is graded

- Up to half of the light sources out in a lamp made of several: minor defect.
- The lamp out, missing, or more than half of its light sources dead: major defect.
- A defective lens over the running light: major defect.
- Colour or intensity not as required, such as light that should be white and is not: minor defect. Heavily reduced intensity: major defect.
- A lamp that is loose: minor. One likely to come away: major.

A car with only minor defects passes and gets its certificate, with the fault recorded. A major defect is a fail. Which line a light falls under is the tester's judgement.

## Why running lights go yellow or die

On many LED units the light is spread along a clear guide, with the LEDs sitting tight against it. Over the years their heat browns the guide, so the light turns dark yellow even though the electronics still work.

Other faults are electrical: a board that fails outright, a section that goes dark, or a light that comes on and drops out a few seconds later. On some cars the running light still uses a bulb, and then it is a bulb change, not a headlight repair.

Yellowing is a known pattern on the SEAT Leon, the Audi A3 and the Renault Mégane 4, among others. The [Audi A3 DRL Repair](https://headlightrepairshop.co.uk/models/audi/a3/) page covers that car in detail.

## How it's put right

Plug-in modules bought online seldom cure a yellowed light, because the colour lives in the guide, not in the module. The fix is a new guide or board inside the original headlight.

On some designs the running light board is reached from the back of the unit without opening it. On most recent units the lens has to come off, the part is renewed, and the lens is bonded and sealed again.

Either way you keep the original headlight, and both sides match afterwards. The work sits under [LED Headlight Repair](https://headlightrepairshop.co.uk/headlight-repair/led-headlights/#daytime-running-lights).

![Opened headlight on a test stand with a new running-light guide glowing evenly white](https://headlightrepairshop.co.uk/img/guides_drl-mot-failure_new-light-guide-lit.webp)

## Questions about running lights at the MOT

### Will a yellow DRL fail the MOT?

Not on colour alone: light that is not the required white is listed as a minor defect, which passes. If it is out, heavily dimmed or more than half dark, it is a major defect and a fail.

### My car was first used before March 2018. Does the DRL matter?

Running lights on those cars are not inspected as DRLs. If yours also works as the front sidelight, it can still be checked as a position lamp.

### Can I fix a yellow running light myself?

Only where it is a bulb. A yellowed LED guide sits inside the sealed unit, so it means opening the headlight and resealing it afterwards.

## MOT coming up?

Send a photo or short video with the running lights on, plus the make, model and year, and say when the test is due. The quote follows before you post anything, and the headlight comes to us by courier within the UK, or is collected where that can be arranged.

[Get a quote](https://headlightrepairshop.co.uk/get-a-quote/)