Many UK drivers assume that leaving a car unused will preserve its condition. However, the opposite is often true. Cars left sitting for long periods fail MOT tests more often because inactivity can cause deterioration in key mechanical and safety components. Regular use helps keep systems working properly, while long-term storage can lead to faults that result in MOT advisories or failures.
Understanding these risks can help vehicle owners prepare their cars properly before the test.
One of the most common MOT failures in unused cars involves the braking system. When a car sits idle, moisture can build up on brake discs, causing corrosion or rust. Over time, this can reduce braking efficiency.
Other brake-related problems include:
Since braking efficiency is a major part of the MOT, these issues can easily lead to failure.
A car battery naturally loses charge over time, especially when the vehicle is not driven. If a car has been sitting for weeks or months, the battery may become weak or completely flat.
This can lead to:
Electrical faults can result in MOT failures if essential systems are not working correctly.
Tyres can also suffer when a car remains stationary for long periods. The weight of the vehicle presses on the same section of the tyre continuously, which can cause flat spots.
Tyres may also:
Tyre condition and tread depth are carefully checked during the MOT.
Suspension components can stiffen or degrade without movement. Rubber bushes may dry out, and shock absorbers may lose effectiveness.
Additionally, fluid leaks may develop as seals dry and shrink. MOT testers check for leaks and suspension wear, which can result in advisories or failures.
You can check previous MOT advisories and identify potential risks early by reviewing your vehicle history at CheckMOT.
Engines that are not used regularly can develop carbon deposits and inefficient fuel combustion. This may cause higher emissions during the MOT test.
Excessive emissions are a common reason for failure, particularly in older petrol and diesel vehicles.
Driving the car regularly helps maintain engine efficiency and reduces this risk.
If your car has been unused, there are steps you can take before the MOT:
These simple actions can improve your chances of passing.
Inactivity causes deterioration in brakes, tyres, battery, and other key components.
Yes. Severe rust can reduce braking efficiency and result in failure.
If it affects essential electrical systems, it can lead to failure.
Problems can begin after just a few weeks without use.
You can check your MOT status and advisories online before your test.