Getting ready for the NCT can be stressful, especially if you are not sure what the tester will check. The good news is that many common NCT failures are caused by simple wear-and-tear items that can be checked before the test.
According to Irish NCT guidance, drivers should pay special attention to common failure points such as headlights, suspension, steering, brakes and handbrake performance before presenting a car for the test. The official NCT checklist also advises drivers to make sure the car has enough oil and water, is reasonably clean, the boot is empty, and the glove box is unlocked for OBD testing.
Below are some of the most common NCT failure areas in Ireland and the car parts or accessories that can help you fix or prevent them.
1. Tyres
Tyres are one of the most common reasons cars fail the NCT. Your tyres can fail for low tread depth, cracks, bulges, uneven wear, incorrect size, or damage to the sidewall.
Before the NCT, check:
- Tread depth
- Tyre pressure
- Cracks or bulges
- Uneven wear
- Matching tyre sizes
- Condition of the spare wheel, if applicable
In Ireland, tyres must have at least 1.6 mm tread depth across the central part of the tyre. However, for safer wet-weather driving, many drivers replace tyres before they reach the legal minimum.
Parts and accessories that can help
- Tyre pressure gauge
- Tyre inflator
- Tread depth gauge
- Wheel nuts
- Valve caps
- Replacement tyres
Tip: If your steering pulls to one side or your tyres are wearing unevenly, get the wheel alignment checked before the NCT.
2. Lights and Bulbs
Faulty lights are another very common NCT issue. A single blown bulb can lead to a fail, so it is worth checking every light before your test.
Check:
- Dipped headlights
- Full beam headlights
- Brake lights
- Indicators
- Fog lights
- Reverse lights
- Number plate lights
- Side lights
- Hazard lights
You should also check that your headlights are not cloudy, damaged, or badly aligned. Headlight alignment is specifically highlighted as an important NCT preparation point.
Parts that can help
- H4 bulbs
- H7 bulbs
- H11 bulbs
- Brake light bulbs
- Indicator bulbs
- Number plate bulbs
- Fog light bulbs
- Headlight restoration kits
- Replacement headlight units
Tip: Ask someone to stand behind the car while you press the brake pedal and test the indicators. Many drivers only discover a blown rear bulb at the test centre.
3. Brakes and Handbrake
Your brakes are one of the most important safety checks in the NCT. The test can identify weak braking performance, imbalance between wheels, worn brake parts, or a poor handbrake.
Common brake-related issues include:
- Worn brake pads
- Worn brake discs
- Weak handbrake
- Brake imbalance
- Brake fluid problems
- Damaged brake hoses
- Sticking calipers
Parts that can help
- Brake pads
- Brake discs
- Brake shoes
- Brake fluid
- Brake cleaner
- Handbrake cables
- Brake calipers
- Brake hoses
Tip: If you hear grinding, squealing, or feel vibration when braking, do not wait until the NCT. Get the brakes checked immediately.
4. Suspension and Steering
Suspension and steering problems are common on Irish roads because potholes, speed ramps and uneven road surfaces can wear out parts over time.
Signs of suspension or steering issues include:
- Knocking noises over bumps
- Car pulling to one side
- Uneven tyre wear
- Steering wheel vibration
- Loose or heavy steering
- Car bouncing after hitting bumps
Parts that can help
- Shock absorbers
- Coil springs
- Wishbones
- Ball joints
- Track rod ends
- Drop links
- Bushings
- Wheel bearings
Tip: If the car feels unstable, noisy, or uneven over bumps, have the suspension checked before booking the NCT.
5. Wipers and Windscreen Washers
Wipers are easy to forget, but they are simple to check and inexpensive to replace. Your car can fail if the wipers do not clear the windscreen properly or if the washer system is not working.
Check:
- Front wiper blades
- Rear wiper blade
- Washer jets
- Screenwash level
- Windscreen cracks or chips
- Wiped area on the windscreen
The NCT checklist includes visibility-related items such as ensuring the wiped areas give the driver an adequate view.
Parts and accessories that can help
- Front wiper blades
- Rear wiper blade
- Screenwash
- Washer pump
- Washer jets
- Windscreen repair kit
Tip: If your wipers leave streaks, make noise, or skip across the glass, replace them before the test.
6. Exhaust and Emissions
The NCT includes emissions testing, so exhaust and engine-related problems can cause a fail. If your car is smoking heavily, has a loud exhaust, or shows a warning light, it is worth investigating before the test.
Common issues include:
- Exhaust leaks
- Damaged catalytic converter
- Diesel smoke
- Engine warning light
- Faulty oxygen sensor
- Poor engine running
- Blocked filters
Parts and products that can help
- Exhaust parts
- Exhaust clamps
- Catalytic converter cleaner
- Diesel fuel treatment
- Petrol fuel treatment
- Oxygen sensors
- Air filters
- Oil filters
Tip: A clean air filter and proper servicing can help your engine run more efficiently before the emissions test.
7. Mirrors, Number Plates and Body Condition
Some NCT failures are caused by simple visual issues. Before the test, walk around the car and check for anything broken, missing, loose, or sharp.
Check:
- Wing mirrors
- Rear-view mirror
- Number plates
- Number plate lights
- Loose bumpers
- Sharp bodywork
- Doors opening and closing correctly
- Boot and bonnet closing securely
Parts that can help
- Replacement wing mirrors
- Mirror glass
- Number plate bulbs
- Number plate holders
- Body clips and fasteners
- Door handles
- Bonnet catches
Tip: Make sure both number plates are clean, secure and clearly visible.
8. Dashboard Warning Lights
Modern NCT testing includes checks related to onboard diagnostics, and warning lights should not be ignored. The official NCT preparation guidance tells drivers to keep the glove compartment unlocked and clear because access may be required for OBD testing.
Warning lights to check include:
- Engine management light
- ABS light
- Airbag light
- Brake warning light
- Power steering warning light
- Tyre pressure warning light
Parts and accessories that can help
- OBD2 scanner
- ABS sensors
- Oxygen sensors
- Battery
- Brake wear sensors
- Airbag-related components
- TPMS valves or sensors
Tip: Do not simply clear a warning light before the NCT. If the fault is still present, it may return during or before the test.
9. Battery and Electrical Issues
A weak battery may not directly be the most obvious NCT failure item, but poor electrical performance can cause warning lights, starting issues, and unreliable lighting.
Signs your battery may need attention:
- Slow engine start
- Clicking noise when starting
- Dim lights
- Battery warning light
- Stop-start system not working
- Electrical faults appearing randomly
Parts and accessories that can help
- Car battery
- Battery charger
- Jump leads
- Battery terminals
- Battery tester
- Alternator belt
Tip: If your battery is several years old and the car is slow to start, test it before colder weather or before your NCT.
10. Fluids and Basic Service Items
Before the NCT, make sure your car has enough oil and water. The NCT preparation checklist specifically reminds drivers to check that the car has adequate oil and water before the test.
Check:
- Engine oil
- Coolant
- Brake fluid
- Screenwash
- Power steering fluid, if applicable
- AdBlue, if applicable
Parts and products that can help
- Engine oil
- Oil filter
- Air filter
- Cabin filter
- Coolant
- Brake fluid
- Screenwash
- Funnel
- Service kits
Tip: If your car is due a service, it is usually best to service it before the NCT rather than after.
Quick Pre-NCT Checklist
Before going to the test centre, check the following:
| Item | What to Check | Useful Parts |
|---|---|---|
| Tyres | Tread, pressure, cracks, bulges | Tyre gauge, inflator, tyres |
| Lights | Bulbs, indicators, brake lights | Headlight bulbs, brake bulbs |
| Wipers | Streaks, washer jets, screenwash | Wiper blades, screenwash |
| Brakes | Noise, vibration, weak handbrake | Pads, discs, brake fluid |
| Suspension | Knocks, pulling, uneven wear | Drop links, shocks, bushings |
| Exhaust | Smoke, leaks, loud noise | Exhaust parts, fuel treatment |
| Battery | Slow start, warning lights | Battery, charger, jump leads |
| Mirrors | Cracks, missing glass, loose housing | Mirror glass, wing mirrors |
| Number plates | Secure, clean, visible | Plate holders, bulbs |
| Fluids | Oil, coolant, washer fluid | Oil, coolant, screenwash |
Final Advice: Fix Small Problems Before They Become Expensive
Many NCT failures are caused by small issues that could have been fixed before the test. A blown bulb, worn wiper blade, damaged tyre, or weak handbrake can cost you time, money and the hassle of a retest.
Before your NCT, spend 15 minutes checking the basics. If you find a problem, replacing the right part before the test can improve your chances of passing first time.
Need Help Finding the Right Part?
Not sure which bulb, wiper blade, battery, brake part or accessory fits your car?
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