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Top 10 most common NCT failures (and how to prevent against them)

Did you know that over a million cars on Irish roads failed the NCT last year!? That's over half of all the cars on the road!

The intersting thing is a lot of these test failures could have been avoided with some simple checks - saving YOU time & money!

The NCT  (National Car Test) is compulsory for all vehicles registered after 1980, usually every two years. If caught using a car without a valid NCT certificate you could get three to five penalty points and a €60 to €90 fine.

Check out the top 10 list of failure reasons below

top 10 common nct test failures



Generally, your suspension will fail on imbalance (one side not working as well as the other) if there is more than a 30% difference between left and right. The failure is usually due to worn out bushes or worn/leaking shock absorbers.  A suspension imbalance will affect your braking and handling so it’s a safety critical fix. It’s probably not something you would be able to test for or fix yourself, but it might be something that you can detect as quite often issues will be accompanied by clunking or creaking as you drive. SHOP SUSPENSION PARTS>>


Tyre Condition

Tyres are nice and easy to check. They need to be correctly inflated (check inside the fuel filler cap for the correct pressures for your car) have more than 1.6mm of tread, not have any visible damage such as cracks, cuts or bulges and must also be “E” marked. They will also need to be the same type and size on each axle (i.e. same tyres on both front wheels or both back wheels)


Headlamp Aim

Headlight aim is one of the most common NCT fails and is simply an adjustment as opposed to something that needs replacement parts. It usually gets thrown out of adjustment when replacement headlight bulbs have been fitted. In most cases it’s probably best to get the alignment checked by a mechanic. Some petrol stations have a headlight alignment board on the wall that can help you check you alignment – worth keeping an eye out for!


Brake Lines/Hoses

Leaking brake hoses are an extremely common NCT fail. The rubber hoses crack and perish over time and can start to leak brake fluid. Obviously your brakes are a safety critical component and need to be in perfect condition. Replacing rubber brake hoses is not a huge job but is probably one best left to the pro’s. The parts are cheap but there is a bit of time involved in replacing them and your hydraulic brake system will need to be bled after the hoses have been replaced. SHOP BRAKE HOSES>>


Brake performance

Overall brake performance is in the top 10 NCT fail list and can be for a number of reasons. It could be an imbalance where one side is working better than the other (this is dangerous because it could have the effect of making the car want to turn every time you hit the brakes) it could be worn pads or discs or quite often its simply a handbrake that needs adjusting. Handbrake cables stretch or seize over time and may need to be replaced. SHOP BRAKE PARTS>>



We already mentioned headlight alignment but general lighting issues are the number 1 NCT fail area. More often than not it’s simply a blown bulb – usually an easy DIY replacement job. Cracked or faded lenses are also common and non-working number plate lights (again usually just a bulb) are massively common. SHOP LIGHTING>>


Brake Lights

Another lighting issue in the top 10 is brake light function. If you’re on your own in the car, a simple way to test if your brake lights are all functioning (there should be 3 brake lights on your car. left, right and high level) is to reverse up to a reflective surface eg shop window, press the brakes and look in your rear view mirror. Check the reflection for 3 fully functioning brake lights that are brighter than your tail lights. You should check your hazards and fog lights while you’re at it. SHOP BRAKE LIGHTS>>



Damaged or rusted bodywork quite surprisingly makes the top 10 NCT failures. However this does include cracked or broken lights, mirrors and panels. SHOP BODYWORK>>



Steering system failures, like suspension failures are usually due to worn out bushes or ball joints. If there is excessive play in your steering then it’s something that should be fixed immediately. Torn steering rack gaiters are also quite common as are leaking power steering pumps. SHOP STEERING>>


Wipers / Visibility

Anything that is deemed to not give you a clear view of the road can be in instant NCT fail. That can include worn out or damaged wiper blades or a cracked or chipped windscreen (particularly if it’s within the drivers line of sight). SHOP WIPERS>>




Write a Comment Close Comment Form
2/25/2020 8:10 PM
Very good and practical advice re NCT, could save that retest!
8/9/2020 11:25 PM
The first time a million cars  seen a mechanic last year was when they went to the NCT centre. Nuff said...!