Tail Light and Brake Light NCT Rules in Ireland
Short answer: the NCT checks your rear lighting as part of the test. According to the National Car Testing Service (NCTS) pre-NCT checklist, brake lights (stop lamps) can fail if they’re missing or not clearly visible, not working, not brighter than the tail lights, not red, insecurely mounted, contain water, or have a missing or broken lens. Registration plate lamps must work and be white. Your tail lights should work too, so it’s worth checking all of them before you go.
Rear lights are among the cheapest things to fix before a test, and one of the easiest to overlook. This guide covers what the NCT looks at and how to check at home. It’s general information, so always check the latest details on NCTS.ie.
Table of Contents
What the NCT checks on your rear lights
The NCTS publishes a pre-NCT checklist so you can spot problems in advance. For the lights at the back of your car, it covers these items.
| Light | Reasons it can fail |
|---|---|
| Brake lights (stop lamps) | Missing or not clearly visible; not working or faulty; not brighter than the tail lights; not red; insecurely mounted; water or moisture inside; lens missing or broken; the brake light switch doesn’t operate correctly |
| Registration plate lamps | Not working, faulty or not fitted; not white; lens missing or broken |
| Indicators | Missing, not working or faulty; lens broken or missing; not amber; water inside |
Notice that a brake light has to be brighter than the tail light beside it. That’s one reason a fault in a shared unit can cause a problem even when both lights seem to work.
What about tail lights?
Tail lights are part of your rear lighting, and a light that isn’t working can be picked up in the test. Testers may also check other lights, such as reversing lights and rear fog lights, if your car has them. Check that every rear light works, is clear and red where it should be, and is securely fixed.
If you’re not sure which lights your car has, our guide to what a tail light is explains the different lights at the back of the car.
Third brake light
Many cars have a third, high-level brake light in the rear window or on the tailgate. If your car came with one, it’s best to make sure it works before the test. The wiring to a tailgate can wear with use, which is a common reason for a fault. Check the latest NCTS guidance if you’re unsure how it’s treated.
How to check your rear lights at home
- Clean the lenses. A dirty lens makes the lights harder to see.
- Turn your lights on and walk around. Check both tail lights, and the number plate lamp.
- Test the brake lights. Ask someone to stand behind while you press the pedal, or reverse up to a shop window and watch the reflection.
- Check the indicators and hazards. Make sure they flash amber at both back corners.
- Test the reversing light if your car has one, and the rear fog light.
- Look at the lenses. Check for cracks, missing pieces, moisture or condensation inside, and loose fittings.
Common rear light problems and how to fix them
- A blown bulb: the easiest fix. See how to replace a tail light bulb or unit.
- A light that won’t work with a new bulb: check the holder, fuse and wiring. Our guide on tail light not working walks through it.
- A cracked lens or water inside: replacement is usually the best fix. A matching used unit is often more affordable than a new one. Browse used tail lights.
- A brake light that isn’t bright enough: look for a failing bulb, a dirty or faded lens, or a fault in the unit, and get it checked.
Don’t forget your headlights
Rear lights are only half of the story. Headlamp aim is one of the most common reasons for failure. Read NCT headlight requirements in Ireland to check the front of your car too.
NCT tail light and brake light FAQs
Will a blown tail light bulb fail the NCT?
A rear light that isn’t working can cause a fail, so replace any blown bulb before your test. It’s usually cheap and quick to do.
Do brake lights have to be brighter than tail lights?
Yes. The NCTS checklist lists brake lights that are not brighter than the tail lights as a reason for failure.
Do rear lights have to be red?
Brake lights have to be red, and the NCTS checklist lists a brake light that isn’t red as a reason for failure. Registration plate lamps must be white, and indicators amber.
Can a cracked tail light lens fail the NCT?
A broken or missing lens, or moisture inside the light, appears on the NCTS checklist as a reason for failure on brake lights and indicators. It’s best to replace a damaged unit before your test.
Can I fit a used tail light and pass the NCT?
Yes, if it’s the right unit for your car, it’s in good condition and it works properly. Check the fit before you buy with our guide on checking compatibility.
Fix your rear lights before your test
Browse used car tail lights in Ireland, or find a repair shop near you.
