Common Reasons to Fail the NCT 

Posted on December 20, 2023

An NCT is every driver’s nightmare. You often think the worse and picture the lengthy repair list and how much it will cost. Nobody wants to fail and have to re-test again. 

Previously, we published an NCT Checklist. It outlines everything that will be covered in the NCT and a checklist on how to pass. We have found there are a few common reasons cars fail the NCT. We created this list so that you can fix any of these potential problems before the dreaded NCT day and hopefully save you money.


There are a few things you can check for yourself without the help of a mechanic. These include the following:

  • Are the lights fully functional?
  • Are the lights cracked or damaged?
  • Are all the lights working?

Another area you will need to pay attention to is the alignment of your headlights. When you try to replace a bulb, issues can arise with headlights, so check the alignment is correct so you can position it appropriately. A mechanic will have this sorted for you in minutes. 

Car Lights

Lastly, check that your brake lights are functional. A helpful way to check if your brake lights are working is to reverse up near a reflective surface and press the brakes. Look in your rear-view mirror to see if they light up. It is also easier to get someone to help with this. Simply press on the brake and ask them to let you know if they light up. 



Another common reason cars fail the NCT is due to suspension issues. Your car will automatically fail if there is an imbalance of more than 30% between suspension on the left and right sides. Other common issues with suspension are:

  • Wear
  • Corrosion 
  • Cracking 
  • Leaking

Suspension is essential to your car’s handling and braking, so the testers put a lot of emphasis on it.


You will receive an instant fail if you cannot get a clear view of the road ahead. If you have damaged wiper blades or cracked/chipped windscreen, you will fail. 

If you have noticed your windscreen wipers are not performing effectively and are hindering your view in the rain, then you should replace them. You can easily replace them yourself, and most insurance policies will include a windscreen cover if your windscreen suffers any damage.



An endless list of reasons your car might fail the NCT due to tyres, such as worn threads and visible damage. You must have matching pairs on each axle and also ensure that there are no:

  • Cuts 
  • Bulges
  • Scratches on the surface

All tyres should be inflated to the recommended tyre pressure set by your manufacturer.

You should check your threads before your car goes for an NCT. On your tyre, there is a Tread Wear Indicator. It may be stamped TWI on your tyre. It is essentially a ribbed bar which runs across the tyre. If you find that your tyre threads are level with the ribbed bar, your tyre will need to be replaced. 

Keep in mind that Ireland’s legal minimum tyre tread depth is 1.6mm. You should not allow your tyres to get near that number as it is potentially dangerous when driving on roads during bad weather conditions. We recommend always keeping your tyres between 4mm and 8mm. 

Brake Lines/Pads

If there are any issues with your brakes, you should get them checked immediately. Not just for the NCT but for your safety. You may not notice issues with your brakes that could fail you. Cars fail the NCT because the rubber hose carrying brake fluid can crack and leak over time. There’s also your typical wear and tear on your brake pads which could fail you if they fall below standards. It is always recommended to get your brakes tested twice a year as they are so important to the function and safety of your car. 


What happens if your car fails the NCT?

If your car fails the NCT, you will have 30 days to get any items repaired and returned to the NCT centre for re-inspection. 

Can you fail an NCT on tyre pressure?

Poor tyre condition is one of the most common reasons cars fail the NCT. The tyre pressure should be at the level the manufacturer has stated.

Will my car fail due to a service light being on?

You are guaranteed to fail immediately if you arrive at the NCT with a warning icon on your dashboard. They may not even conduct the test because a warning light on means there is an issue without even checking. 

What is the penalty for driving a car with no NCT?

Driving a vehicle in Ireland without a valid NCT Certificate is illegal. The penalty for doing so is a fine of up to €2000, and/or up to 5 penalty points and/or imprisonment for up to 3 months. 

How much does an NCT Re-test cost?

The fee for an NCT re-test is €28. If the re-test does not require any test equipment and is strictly visual, it will be free of charge. For example, it is a simple visual check to see if a faulty windscreen wiper is replaced. 

Like an NCT certificate, holding a valid car insurance policy is essential for driving in Ireland. If you are looking for a competitive quote on your car insurance, get an online quote from us here and see how we compare to your current premium. 

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