Once a vehicle is over three years old, it will require an MOT test to ensure the vehicle is roadworthy.
The test covers a number of aspects to check if the vehicle meets all of the required safety and environmental standards.
If you are curious to understand what will be checked during an MOT test, the Filter Services team have put together the following guide so that you know what to expect at the time of writing in 2026.
Legal Checks & General Vehicle Condition
Before inspecting the vehicle itself, the first step is some housekeeping to ensure the number plate conforms to UK regulations (spacing and font). The number plates should also be securely held in place.
Next, they will check that the VIN number is also visible. The MOT due date, insurance and tax will also be checked.
Before getting under the hood, the outer layers of the vehicle will be inspected. The technicians will be looking to ensure that the bodywork has no sharp edges, major damage or rust near structural points.
Brakes
Brakes are one of the most safety-critical elements of the MOT. Inspectors check the condition and operation of the foot brake and handbrake, including brake pads, discs, drums, cables and hydraulic components. Brake efficiency is also tested using a rolling road brake tester to confirm that braking force meets the required standard across all wheels.
Exhaust And Emissions
The exhaust system is inspected for leaks, damage and secure mounting. Emissions are also tested to confirm the vehicle meets the environmental standards appropriate for its age and fuel type. Petrol vehicles are tested for hydrocarbons and carbon monoxide levels, while diesel vehicles are assessed for the opacity of exhaust smoke.
Fuel System
The fuel system is checked for leaks and the condition of fuel caps, pipes and connections. Any sign of a fuel leak is an immediate MOT failure on safety grounds.
Horn
The horn is checked to confirm it works and produces a continuous, loud enough sound. This is one of the simpler checks but a non-functioning horn is still an MOT failure point.
Lights And Electrical Systems
All exterior lights are checked during an MOT, including headlights, tail lights, brake lights, indicators, hazard lights, fog lights and reversing lights. Inspectors check that each light works correctly, is properly aligned and is not cracked or obscured. A blown bulb or misaligned headlight is one of the most common reasons for an MOT failure and one of the easiest to fix before the test.
Seatbelts
Every seatbelt in the vehicle is checked for condition and correct operation. Inspectors look for fraying, damage to the webbing and confirm that buckles and retractors work as intended. A seatbelt that fails to lock or retract properly will result in an MOT failure.
Steering And Suspension
The steering system is checked for excessive play, wear and correct operation. Suspension components including shock absorbers, springs and joints are inspected for damage, corrosion and deterioration. Poor steering response or a vehicle that pulls to one side are common indicators of issues in this area ahead of a test.
Tyres And Wheels
All four tyres are inspected for tread depth, condition and correct fitment. The legal minimum tread depth in the UK is 1.6mm across the central three quarters of the tyre, though many safety experts recommend replacing tyres before they reach this point. Inspectors also check for cuts, bulges and uneven wear that could indicate a deeper mechanical issue, as well as confirming that all tyres on the same axle are of the same type and size.
Vehicle Identification
Inspectors confirm that the vehicle identification number (VIN) is present and matches the registration documents. The number plate is also checked for correct font, spacing and legibility.
Windscreen And Visibility
The windscreen is inspected for damage within the driver’s line of sight. A chip or crack larger than 10mm in the swept area directly in front of the driver, or larger than 40mm anywhere else in the windscreen, will result in a failure. Windscreen wipers and washers are also tested to confirm they clear the screen effectively.
Types Of Filters That Can Affect Your MOT
Since we specialise in vehicle filters here at Filter Services UK, we think it’s important to also cover how each filter type can impact your MOT.
Diesel Particulate Filter (DPF) – Diesel Vehicles Only
The DPF reduces harmful emissions by trapping soot from the exhaust. It’s a legal requirement to have DPF for most modern diesel cars (especially post-2009 Euro 5 and later).
If the DPF has been removed, tampered with or is not functioning properly, your car will fail the MOT. In addition, if there is visible smoke from the exhaust during the emissions test, it’s also a fail.
A DPF warning light illuminated on the dashboard is a major fault and an MOT fail.
Air Filter
A clean air filter ensures efficient engine performance and good fuel combustion.
While not checked directly, a clogged air filter can lead to increased emissions, potentially causing an emissions test fail.
It can also cause poor running or hesitation, which might affect how the tester perceives the car’s roadworthiness.
Fuel Filter
The fuel filter ensures clean fuel is delivered to the engine, which helps maintain proper engine operation and emissions control.
Like the air filter, it is not inspected directly during an MOT. However, if the filter is blocked, the engine may run poorly or stall. This could indirectly cause a failed test due to excessive emissions or engine misfire.
Oil Filter
The oil filter keeps the engine oil clean and flowing properly to help protect the engine.
It is also not checked directly. However, if neglected, it can cause oil leaks or engine issues which could also lead to a potential test failure.
What Happens If My Car Fails Its MOT?
If your vehicle fails its MOT, you will receive a list of the reasons for failure. Minor faults classed as advisories do not prevent you from passing but should be monitored and addressed. Major and dangerous faults must be repaired before the vehicle can be driven legally on a public road, with the exception of driving directly to a pre-booked repair appointment.
If your existing MOT certificate is still valid when your car fails a retest, you can continue to drive it until that certificate expires, provided no dangerous faults were recorded.
How To Prepare For An MOT
Checking your lights, tyre tread depth, windscreen condition and wiper operation before your test takes only a few minutes and can help you avoid a failure on straightforward issues. Ensuring your vehicle is clean enough for the inspector to carry out checks properly, and that the fuel tank has enough fuel for an emissions test, are also worth attending to ahead of your appointment.
Filter Services – Discover Our Vehicle Filters & Accessories
There’s lots to consider when your vehicle is due its MOT. One such aspect is the quality and overall condition of its filters, as vehicle filters can impact the engine, fuel efficiency and emissions.
If you require any filters for your vehicle, then head over to our filters page to view our available stock.
Filter Services is based in Chesterfield with additional locations in Leeds and Leicester.
For any help or enquiries please send us a message or give us a call on 01246 802 822.