NEW: Why Your Car Will Probably Fail The NCT

NCT statistics

Based on the official NCT statistics compiled by Applus (the company that operates the National Car Test), the top five reasons vehicles fail the NCT have been remarkably consistent year on year.

Here they are:

1. Steering and Suspension

This tops the list, accounting for around 15% of all failures.  Worn shock absorbers, broken springs, perished bushes and play in steering joints are the usual culprits, and Irish road conditions (potholes in particular) take much of the blame.

2. Lighting and Electrical

The second most common reason for a fail, at around 14%.  This covers blown bulbs, cracked lenses and, notably, misaligned headlights.

Misaligned headlights are the number one failure among the non-visual defects picked up by testing equipment.

3. The Side Slip Test (Wheel Alignment)

The third most common failure, this measures how well a car maintains a straight line when driven without steering input.

Excessive deviation indicates misaligned wheels, often caused by kerb or pothole impacts.

4. Tyres and Wheels

Accounting for roughly 10% of all failures.  Tread depth below the legal 1.6mm minimum, sidewall damage, cracking on older tyres and mismatched tyres all feature. Tyre issues alone were behind around 75,000 “needless fails” in a single year.

“Needless” because they’re the easiest defect for an owner to spot and fix in advance.

5. Brakes

Brake imbalance (where one side brakes harder than the other), worn pads and discs, and a handbrake that won’t hold are the common issues here.

Corroded brake lines are a particular problem given Ireland’s damp climate.

For context on the scale of it: over 1.7 million NCTs were carried out in 2025, and well over half — 885,904 — failed the full test.

That’s a failure rate of just under 51%.

So while the odds are slightly against you passing first time round, it’s unlikely you’ll be left car-less.

If at first you don’t succeed…