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What Happens During an MOT Test?

The MOT test ensures UK vehicles meet safety and environmental standards. Learn about the inspection process, pre-test checks, and maintaining roadworthiness.

Introduction to the MOT Test

What is an MOT?

The MOT, or Ministry of Transport test, is an annual vehicle inspection required in the United Kingdom for most vehicles over three years old. The primary purpose of the MOT is to ensure that vehicles on the road meet specific safety and environmental standards.

The abbreviation “MOT” stands for the Ministry of Transport, the government department responsible for introducing the test in 1960 as a means of testing vehicle safety, exhaust emissions, and roadworthiness.

Importance of the MOT Test

The MOT test is crucial for maintaining road safety and environmental standards in the UK. By rigorously examining key components such as brakes, lights, tires, and exhaust emissions, the test helps ensure that vehicles on the road are roadworthy and meet legal requirements.

The MOT test is not just a legal requirement but also a means to ensure vehicle safety and contribute to environmental preservation. By identifying and addressing potential issues, the test helps maintain the overall safety of UK roads and reduces the risk of accidents and breakdowns.

Key Areas Inspected During the MOT Test

The MOT test involves a comprehensive examination of various vehicle components to ensure they meet the required standards. Some of the key areas inspected during the test include:

  • Brakes and brake system components
  • Lights, reflectors, and electrical equipment
  • Tires and wheels (including tread depth and condition)
  • Seat belts and airbags
  • Body structure and general items (such as doors and mirrors)
  • Exhaust system and emissions
  • Driver’s view of the road (including windshield and mirrors)

    It’s important to note that the MOT test does not cover the general mechanical condition of the engine, clutch, or gearbox. Its primary focus is on safety-related components and emissions standards.
The MOT test ensures UK vehicles meet safety and environmental standards. Learn about the inspection process, pre-test checks, and maintaining roadworthiness.

Before the Test: Preparing Your Vehicle

Pre-MOT Checks You Can Perform at Home

Conducting a few basic checks on your vehicle before its MOT can increase the chances of passing the test and save you from costly repairs down the line. Here are some essential pre-MOT checks you can perform at home:

Lights and Indicators

  • Turn on all exterior lights (headlights, taillights, brake lights, indicators, etc.) and walk around the vehicle to ensure they are functioning properly.
  • Check that the indicators are flashing at the correct rate and that all bulbs are working.


  • Check that the tyre tread depth meets the minimum legal requirement of 1.6mm across the central three-quarters of the tread, around the entire circumference.
  • Inspect tyres for any cuts, bulges, or other damage that could lead to a failure.
  • Check that the tyre pressures are set to the recommended levels for your vehicle.

Windscreen and Wipers

  • Ensure the windscreen is free from cracks, chips, or other damage that could obstruct the driver’s view.
  • Check that the windscreen wipers are in good condition and can effectively clear the windscreen.

Other Checks

  • Ensure the registration plates are securely attached, legible, and conform to legal requirements.
  • Check that all mirrors are securely attached and provide a clear view.
  • Test the operation of the handbrake, seatbelts, and other safety features.

Benefits of Addressing Known Issues

By identifying and addressing any potential issues before the MOT, you can:

  • Increase the likelihood of passing the test on the first attempt, saving you the hassle and cost of a retest.
  • Avoid costly repairs or failures due to issues that could have been addressed earlier.
  • Ensure your vehicle is in top condition, improving its overall safety and reliability.

Remember, while these pre-MOT checks can help identify potential issues, they do not replace the comprehensive inspection performed during the official MOT test.

Exterior Inspection

During the exterior inspection, the MOT tester thoroughly examines the vehicle’s body condition, doors, mirrors, and registration plates. This comprehensive check is crucial to ensure the safety and roadworthiness of the vehicle.

Body Condition

The inspector assesses the overall condition of the vehicle’s body panels, undertrays, spoilers, and mirror housings. Any damage, corrosion, or insecure components that could potentially cause injury when grazed or contacted will result in a failure. Additionally, the inspector checks for any modifications that may adversely affect the braking or steering systems.

Doors and Door Catches

  • The tester ensures that the front doors can open from both the inside and outside of the vehicle.
  • Rear doors must be able to open from the outside.
  • All door hinges and catches are inspected for security and proper condition.
  • Any defects that could prevent the doors from opening or closing securely will lead to a failure.


The inspector verifies the presence of the minimum required number of mirrors and checks their condition and security. Any indirect vision devices, such as camera systems, are also inspected. Damaged or insecure mirrors can result in a failure.

Registration Plates

The vehicle’s registration plates are examined for their condition, secure attachment, correct color, and properly formed and spaced characters. Any defects or illegibility of the registration plates can lead to a failure.

Lighting and Signal Functionality

Lights Inspected

  • Headlights (main beam and dipped)
  • Sidelights (front and rear)
  • Indicators (front, rear, and side repeaters)
  • Brake lights
  • Rear number plate light
  • Rear fog light
  • Hazard lights

The tester checks the condition, operation, and aim of all lights, including high-intensity discharge (HID) and light-emitting diode (LED) systems. Any malfunctioning or damaged lights will result in a failure.

Signal Functionality

Proper functioning of the vehicle’s signal lights is essential for safety. The inspector ensures that all indicators, including front, rear, and side repeaters, are working correctly. Any issues with the signal lights can lead to a failure. By conducting a thorough exterior inspection, the MOT test ensures that the vehicle’s body, doors, mirrors, registration plates, and lighting systems meet the necessary safety standards for roadworthiness.

Interior and Safety Checks

During an MOT test, the interior of the vehicle undergoes a thorough inspection to ensure the driver’s safety and visibility. Here are the key areas that are checked:

Driver’s View


The windscreen is carefully examined for any cracks, chips, or damage that could obstruct the driver’s view. Chips or cracks larger than 10mm in the driver’s line of vision (a 290mm wide area centered around the steering wheel) will result in an MOT failure. Outside this area but still within the wiper blade sweep, the maximum allowable damage size is 40mm.


All mirrors, including the rear-view mirror and side mirrors, are inspected to ensure they are securely fitted and provide a clear view to the rear and sides of the vehicle. Indirect vision devices like rear-view cameras will also be checked for proper functioning.

Windscreen Wipers and Washers

The windscreen wipers and washers are tested to ensure they are in good working condition and can effectively clear the windscreen, as stated in the MOT inspection manual.

Safety Systems

Seat Belts

All seat belts in the vehicle are checked for proper operation, condition, and security. The MOT tester will ensure that seat belts are not excessively worn, frayed, or damaged.


The airbag system is inspected to ensure it is functioning correctly. The MOT tester will check the airbag warning light to ensure the system is operational.

Other Safety Features

Other safety features, such as the horn, speedometer, and electronic stability control (ESC), are also checked during the MOT test, as outlined in the MOT inspection manual. By thoroughly inspecting the interior and safety systems, the MOT test ensures that the vehicle meets the necessary safety standards for road use, providing peace of mind to drivers and other road users alike.

Under the Hood and Vehicle Undercarriage

Engine and Fluid Checks

During the MOT test, inspectors thoroughly examine several critical components under the vehicle’s hood. One crucial area is the engine and its related systems. While the engine’s internal condition is not directly assessed, certain external components are carefully inspected:

  • Engine mountings: The mountings that secure the engine to the vehicle’s frame are checked for excessive wear, corrosion, or fractures that could lead to unsafe movement or detachment.
  • Fluid levels: Although low fluid levels themselves do not lead to an automatic failure, inspectors may issue an advisory if they notice insufficient engine oil, coolant, or other vital fluids.
  • Fluid leaks: Significant fluid leaks, such as oil or coolant leaks, can result in a failure if deemed severe enough to pose a safety risk or environmental hazard.

Exhaust System Inspection

The exhaust system is another critical component that undergoes rigorous inspection during the MOT test. Inspectors check for the following:

  • Leaks: The entire exhaust system, including the manifold, pipes, silencers, and catalytic converters, must be free from significant leaks that could pose a safety risk or cause excessive noise.
  • Secure fittings: All components of the exhaust system must be securely mounted and properly attached to the vehicle using the intended mounts or hangers.
  • Emissions testing: Vehicles are subjected to emissions testing to ensure they comply with legal limits for exhaust pollutants. The specific test method varies based on the vehicle’s age and fuel type.

Undercarriage Inspections

The undercarriage of the vehicle is also thoroughly inspected during the MOT test, with a focus on the following components:

  • Wheels and tyres: Inspectors check for proper tyre tread depth, sidewall damage, correct tyre size and speed rating, and proper inflation. The tyre pressure monitoring system (TPMS) is also tested for functionality.
  • Brakes: The condition and operation of the brake system, including brake pads, discs, and fluid levels, are thoroughly evaluated to ensure proper functionality and safety.
  • Suspension: Inspectors assess the condition of the vehicle’s suspension components, such as shock absorbers, springs, and suspension arms, for signs of excessive wear, corrosion, or damage that could compromise vehicle handling and safety.
  • Battery and connections: The battery must be securely mounted, and its connections must be tight and free from corrosion or leaks.

It’s important to note that while the MOT test does not cover the internal condition of the engine, transmission, or clutch, it comprehensively evaluates the safety and roadworthiness of numerous external components that are critical for safe vehicle operation.

Emissions Testing

Purpose and Process of Emissions Testing

Emissions testing plays a crucial role in monitoring and controlling the release of harmful pollutants from vehicles into the environment. The primary objective is to analyze the exhaust gases to ensure they comply with legal limits for greenhouse gases and other pollutants like carbon monoxide, hydrocarbons, and nitrogen oxides (NOx).

Testing Procedure

For modern vehicles, emissions testing is typically conducted by connecting the car to a testing system through the onboard diagnostics (OBD2) port. Older models without an OBD2 port are tested by placing the car on a dynamometer (a treadmill-like device) and attaching a sensor to the tailpipe.

During the test, the vehicle is put through a series of prescribed driving cycles while the emissions are measured and analyzed. The testing equipment measures the density and composition of the exhaust gases, including the size and quantity of particulate matter.

UK Legal Requirements for Exhaust Emissions

MOT Emissions Test

In the UK, most vehicles have their exhaust emissions tested as part of the annual MOT (Ministry of Transport) inspection. The emissions are typically measured using a meter, while older petrol and diesel vehicles are tested visually for smoke. Failing the emissions test results in an MOT failure.

Emissions Standards and Limits

The UK follows the European Union’s “Euro” emissions standards, which have become increasingly stricter over time. The current standard is Euro 6, which sets limits for various pollutants, including nitrogen oxides (NOx) and particulate matter (PM) from diesel vehicles.

For example, from July 2025, all new petrol and diesel cars sold in the UK must comply with the upcoming Euro 7 standard, which will further tighten emissions limits, with a maximum of 60 milligrams of NOx per kilometer.

Clean Air Zones and ULEZ

To improve air quality, the UK has introduced Clean Air Zones in various cities, where vehicles must meet minimum emissions standards to avoid charges. For example, in London’s Ultra Low Emission Zone (ULEZ), cars must meet Euro 6 (diesel) or Euro 4 (petrol) standards to avoid paying a daily fee.

Consequences of Failing Emissions Tests

If a vehicle fails an emissions test during the MOT or a roadside check, the owner will typically receive a prohibition notice and have 10 days to rectify the issue. Failure to do so may result in prosecution.

Common reasons for emissions test failures include faulty oxygen sensors, worn spark plugs, and issues with the catalytic converter or diesel particulate filter (DPF). Repairs can range from simple fixes like replacing air filters to more expensive repairs like catalytic converter replacement, depending on the vehicle and extent of damage.

The MOT test ensures UK vehicles meet safety and environmental standards. Learn about the inspection process, pre-test checks, and maintaining roadworthiness.

After the Test and Maintaining Roadworthiness

Potential Test Outcomes

After completing the comprehensive MOT inspection, there are three potential outcomes:

  1. Pass: Your vehicle meets all the minimum legal standards for safe operation on public roads. You will receive a test certificate, and your vehicle’s details will be updated in the MOT database.
  2. Pass with Advisories: While your vehicle has passed the MOT, the examiner has identified minor issues or potential future problems. These advisories are listed on the certificate, and you should address them promptly to maintain your vehicle’s roadworthiness.
  3. Fail: If your vehicle fails the MOT due to one or more major or dangerous defects, you cannot legally drive it on public roads until the necessary repairs are made and it passes a follow-up test.

Next Steps After the Test

If Your Vehicle Passes

  • You can continue driving your vehicle legally for another year, provided no significant issues arise.
  • If you received advisories, address them promptly to maintain your vehicle’s safety and roadworthiness.
  • Keep your test certificate in a safe place as proof of your vehicle’s MOT status.

If Your Vehicle Fails

  • Do not drive your vehicle until the necessary repairs are made and it passes a follow-up test.
  • Discuss the test results with the examiner and arrange for repairs at a reputable garage.
  • Once repairs are complete, contact the MOT test center to schedule a partial or full retest within 10 working days.
  • If you believe the failure is incorrect, you can appeal the decision with the Driver and Vehicle Standards Agency (DVSA) within 14 working days.

Maintaining Roadworthiness

Passing the annual MOT is crucial, but it does not guarantee your vehicle’s continued safety and reliability throughout the year. Regular maintenance is essential to ensure your vehicle remains roadworthy and to avoid potential breakdowns or accidents.

  • Follow the manufacturer’s recommended service schedule for routine maintenance, such as oil changes, fluid checks, and filter replacements.
  • Inspect your vehicle regularly for any signs of wear or damage, and address issues promptly.
  • Keep up with routine checks, such as monitoring tyre tread depth, checking lights and signals, and testing brakes and suspension components.
  • Proper maintenance can improve fuel efficiency, extend your vehicle’s lifespan, and ultimately save you money in the long run.

By understanding the potential outcomes of the MOT test and taking appropriate action, you can ensure your vehicle remains safe, legal, and reliable on the road.

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