Common Causes for NCT Failure

Common Causes for nct Failure

One of the most inconvenient times of the year is when your car is due to an NCT test. The car may feel like it is in top condition to you, but the testers may be able to find a fault that you don’t know about. Their say is final, so it is vitally important that your car is fully prepared for taking the test. Less than half of all cars tested for the NCT pass on the first go. To ensure that you don’t fall into this category here are some of the most common reasons that cars fail the NCT.

Tyre thread Depth and Damage:

You will almost certainly fail the NCT if your tyre depth is below the legal limit, if there is any damage to your tyres or if your tyres are mismatched size and shape. Luckily these issues can be fixed. The legal minimum requirement for tyre thread depth is 1.6mm. This depth should be even greater during the winter, but it only needs to be greater than 1.6mm to pass the NCT. Tyres also need to be the same type and size on each axle. There needs to be a visible E-mark on each tyre, denoting EU approval.

Suspension Failure:

After an analysis of over 1.2 million cars in 2015, it was determined that the most common reason for NCT failure was due to Suspension Failure. This can be caused by either an imbalance or damage to the suspension. If there is more than a 30 percent imbalance between left and right-hand suspension. It’s best to have a professional mechanic look at the suspension as it’s one of the more complicated car parts.


In the NCT both of your headlights and break lights will be checked to ensure all are in working order. It is not only the condition of the bulbs that will be checking. The alignment of the headlights will also be checked. This is a very quick and easy fix for any car owner. It should be one of the first things that you check before bringing the car to the NCT.


This should be a given as they are a major component in terms of car safety. Outside of the NCT your cars brake pads and lines should be checked on a regular basis. You don’t want a build-up of wear and tear on any part of the braking system as it can limit your ability to brake or even prevent you from braking altogether. Get a professional mechanic to check and repair your brakes if necessary.

There is no guarantee that you will pass your NCT on the first try even if you have checked all the parts we have mentioned here. It is also important to have all your information related to the vehicle close to hands such as your Car Insurance, tax, and registration.

Suhail is a journalist who loves everything about technology driven cars. He keeps a keen eye on the latest developments in automotive industry and shares the news as it breaks.

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