The NCT — National Car Test — is Ireland's mandatory roadworthiness test for cars over four years old. Knowing what the testers check, what the most common failure items are, and how to prepare your car can save you the cost of a retest and identify problems before they become expensive repairs.
The short answer
The NCT costs €55 and tests over 40 aspects of your vehicle's condition. The most common failure reasons in Ireland are: lighting faults (blown bulbs or failed headlight aim), tyre issues (tread depth, condition, age), brake imbalance or low pad thickness, and emissions failures on older diesels. A basic preparation check before the test — all bulbs working, tyres above 1.6mm tread, no warning lights — eliminates the most common avoidable failures. Book at ncts.ie.
When does your car need an NCT?
The schedule depends on the car's age:
- 4 years old: First NCT due
- 4–10 years old: Every 2 years
- 10 years and older: Every year
The due date is printed on the NCT disc displayed on your windscreen. You can also check online at ncts.ie using your car's registration number — it's free and takes 30 seconds. It's also the first check Autoza recommends before viewing any used car.
How much does the NCT cost?
- Standard NCT test: €55
- Retest (within 21 days, same items that failed): €28
- Retest (after 21 days): Full €55 fee
You can book online at ncts.ie or by phone. Cancellations with less than 5 working days' notice incur a fee.
What does the NCT test check?
The NCT follows the EU Roadworthiness Testing Directive and tests over 40 items across 9 categories:
1. Lighting and electrical
- All exterior bulbs: headlights, rear lights, brake lights, indicators, fog lights, reversing light
- Headlight alignment: tested with a beam meter — aim must be within tolerance
- Hazard warning lights, horn, number plate illumination
2. Steering and suspension
- Steering play: checked for excessive movement in the steering wheel
- Steering rack condition: tested for leaks, play, and secure mounting
- Shock absorbers: emission-plate test checks damping efficiency
- Suspension joints: ball joints, track rod ends, tie rods checked for wear and play
- Wheel bearings: checked for roughness
3. Brakes
- Brake efficiency: all four wheels tested individually on a brake roller rig
- Brake balance: left/right balance on each axle — imbalance causes a fail
- Handbrake efficiency
- Brake fluid: contamination testing
- Visible brake condition: pad thickness inspected where visible through alloys
4. Tyres
- Tread depth: minimum 1.6mm across the central ¾ of the tread width
- Tyre condition: cuts, bulges, exposed cord, uneven wear
- Tyre age: tyres over 10 years old are flagged for replacement (currently an advisory, not an automatic fail in Ireland — but will be tightened)
- Spare tyre: checked for condition if a full-size spare is fitted
5. Emissions
- Petrol engines: CO and HC measured at idle and fast idle
- Diesel engines: Free-acceleration smoke opacity test (the "revving" test)
- DPF check: Since 2014, testers visually check that the DPF (diesel particulate filter) has not been removed
- OBD diagnostic scan: Engine management warning lights checked; active fault codes are recorded
6. Body and structure
- Visible corrosion or structural damage to the chassis, floor, and sills
- Doors: open, close, and latch correctly
- Bonnet latch: both primary and secondary catches
7. Glass
- Windscreen: chips or cracks in the driver's direct line of sight (Zone A) are a fail
- Rear window and mirror condition
- Windscreen wipers: must clear the screen effectively
- Washer system: front and rear
8. Interior
- Seatbelts: all belts must retract, latch, and release correctly; no cuts or fraying
- Seats: driver's seat must be secure
- Speedometer: must function
- Fuel cap: must seal
9. Under the bonnet / underbody
- Fluid leaks: oil, coolant, power steering, brake fluid
- Battery mounting: must be secured
- Exhaust system: checked for leaks, secure mounting, corrosion
Most common NCT failure reasons in Ireland
Based on NCTS published data, these are the most frequent failure categories:
- Lighting (lamps): Number one failure category. A single blown bulb is a fail. Check all bulbs before presenting for test.
- Tyres: Tread depth below 1.6mm or damaged sidewalls. Check across the full width — not just the centre.
- Brake imbalance: Often caused by a sticking rear caliper or seized handbrake cable — more common on cars that are not regularly driven hard enough to clean rust off the brake surfaces.
- Suspension and steering components: Worn ball joints, track rod ends, and shock absorbers are common on cars above 100,000 km on Irish roads.
- Emissions (diesel): DPF issues are increasingly common — especially on short-journey city cars that never fully regenerate the filter.
- Windscreen chips in Zone A: A chip in the driver's primary view that is larger than 10mm, or any crack in this zone, is a fail.
How to prepare your car before the NCT
A 30-minute pre-test check eliminates most avoidable failures:
- Walk around all exterior lights at night or in a dark area. Check headlights (main beam and dipped), rear lights, brake lights (you need someone to press the pedal), indicators front and rear, fog lights, reversing light, and number plate light. Replace any blown bulbs — LED conversions in reflector housings can cause headlight aim failures; stick to OEM-style bulbs unless your car has proper LED projectors.
- Check tyre tread with a 20c coin. The band around the edge of a 20 cent coin is approximately 2mm — if you can see the entire band, replace the tyre before the test. Check across the full tread width, not just the centre.
- Check for warning lights. Clear any warning lights you know are trivial (e.g. service reminder). Any EML, ABS, traction control, airbag, or TPMS light that remains on during the test is a fail.
- Test windscreen wipers and washers. Both should work and washers should have fluid.
- Check for windscreen chips in your direct line of sight. If in doubt, get a windscreen repair (often covered by car insurance with no excess) before the test — repairs are much cheaper than replacements and a repaired chip will pass if properly done.
- Test all seatbelts. Each belt should extend and retract smoothly and click into the buckle with a positive lock.
- For diesels: take a 20-minute motorway drive before the test. This helps the DPF regenerate and reduces the chance of an opacity test failure. Avoid lots of stop-start driving immediately before your test appointment.
What happens if your car fails?
If your car fails, you receive a Failure Report listing each failed item. You have two options:
- Retest within 21 days: Have only the failed items repaired and return for a free (or reduced-cost €28) retest. The retest only retests the failed items.
- Retest after 21 days: Full test required, full €55 fee.
You may still drive the car legally for up to 21 days after a failure to get the repairs done — but only for the purpose of getting the car repaired and returned for retest. You cannot legally drive a failed car generally.
NCT advisories vs failures
The tester may also record Advisories — items that are not a fail today but are approaching the threshold for failure. Common advisories include: tyres approaching the minimum tread depth, minor corrosion visible but not yet structural, a small windscreen chip in a non-critical zone. Advisories are warnings to monitor and repair before the next test.
Buying a used car near its NCT date
When buying a used car, always check the NCT status first at ncts.ie. If the NCT is due within 3–6 months, factor in the €55 test fee and potential repair costs. A car with 18 months+ remaining NCT is meaningfully more convenient than one due imminently. And never buy a car with a long-expired NCT without a full pre-purchase inspection — an expired NCT means the car hasn't been independently checked recently.
