The National Car Test (NCT) is Ireland’s roadworthiness inspection. Every car over 4 years old must pass it, and it’s repeated every 1–2 years depending on age. The fail rate is around 50% on first attempt — but most failures are for easily preventable issues.
What Does the NCT Check?
The NCT is a visual and mechanical inspection covering:
- Brakes — efficiency, balance, handbrake. This is the #1 failure category.
- Lights — all bulbs working, headlight alignment, lens condition
- Tyres — tread depth (minimum 1.6mm), condition, correct size
- Suspension — shock absorbers, springs, ball joints, bushings
- Steering — play in the steering, power steering condition
- Exhaust & emissions — CO and HC levels, exhaust leaks, catalytic converter
- Body & chassis — rust, structural integrity, seatbelt anchorage
- Windscreen & wipers — chips, cracks, wiper effectiveness
- Seatbelts — operation, webbing condition, buckles
Top 5 NCT Failure Points (And How to Fix Them)
1. Headlight Alignment (15% of failures)
Your headlights are tested on a beam machine. Even slightly misaligned headlights will fail you. Fix: Any garage can adjust headlight alignment for €20–40. Do it the week before your test.
2. Brake Performance (12% of failures)
Brakes are tested on a roller. Worn pads, sticky calipers, or imbalanced braking will fail. Fix: Get brake pads and discs checked. Budget €150–300 per axle if they need replacing.
3. Tyres (10% of failures)
Tread depth below 1.6mm, uneven wear, or damage to the sidewall. Fix: Check with a 1 euro coin — if you can see the gold rim, the tread is too low. Replace tyres in pairs (same axle).
4. Emissions (8% of failures)
Diesel cars are especially vulnerable. A clogged DPF or worn injectors can push emissions over the limit. Fix: A long motorway drive (30+ minutes at 100 km/h) before the test helps clear the DPF. For persistent issues, a DPF clean costs €150–250.
5. Suspension (7% of failures)
Worn shock absorbers, broken springs, or perished bushings. Fix: Bounce each corner of the car — if it bounces more than once, the shocks are worn. Budget €200–400 per pair for replacement.
Pre-NCT Checklist
Do this the week before your NCT:
- Check all lights work (headlights, indicators, brake lights, reversing lights, fog lights)
- Check tyre tread depth and pressure
- Top up washer fluid
- Clean the windscreen inside and out
- Check wiper blades aren’t torn
- Make sure the horn works
- Check handbrake holds on a hill
- Remove any dashboard warning lights (especially ABS, airbag, engine)
What Happens if You Fail?
You get a 21-day window to fix the issues and return for a free partial retest. Only the failed items are retested. If you miss the 21 days, you’ll need to pay for a full retest.
Thinking about buying a used car? Always check when the NCT is due and run a free vehicle check on Motorly to see the car’s full history.