Dangerous MOT Failures Explained

A car’s annual MOT test is a legal requirement designed to ensure that vehicles meet the minimum safety and environmental standards to be roadworthy.

It's not just a routine check-up - it's a critical assessment of whether your vehicle is safe to drive.

One of the key aspects of an MOT test is understanding what happens when a car fails the MOT. In particular, what it means when a car fails and the component is deemed as ‘Dangerous’.

What Makes an MOT Failure Dangerous?

The definition of Dangerous MOT failures was updated back in 2018. 

Before then, a test was either given the score of a pass or fail. Following this, the tester would mark on the report components they believed were dangerous.

From the 20th of May 2018, however, the DVSA introduced predefined defects. Meaning if a defect that fell into this bracket was found, it was automatically deemed as dangerous by definition.

Since then, a car that has a dangerous defect marked on its test will fail the MOT, as these are issues that could affect the safety of road users and/or have a substantial negative impact on the environment.

If a car is deemed to have a Dangerous issue, it is not allowed to be driven in any circumstances.

Before the car can be driven, it must first have the appropriate repairs carried out that fix the dangerous component.

Can I drive with a dangerous MOT defect?

If your car has not passed the MOT test and parts have been declared as ‘Dangerous’ you are not allowed to drive the car.

Dangerous MOT Fail Components

There are currently 7 different vehicle system/component parts of a car that can lead to a ‘Dangerous’ MOT Fail.

Which would result in you not being able to drive your vehicle until the car has been fixed.

Axles, wheels, tyres and suspension

This category covers the structural integrity and function of key load-bearing and motion components.

There are 31 specific dangerous MOT fail items in this section, including dangerously worn tyres, broken suspension arms, or cracked wheels. These issues can severely compromise the vehicle’s handling, stability, and safety — making it illegal and unsafe to drive until repairs are made.

Body, structure and attachments

This includes the car’s main shell, chassis, doors, bumpers, tow bars, and other fixed parts.

The MOT manual lists 21 dangerous fail items for this area. These typically involve excessive corrosion, insecure body panels, or sharp edges that pose a threat to pedestrians or other road users.

Such issues are serious enough to require immediate attention before the vehicle is allowed back on the road.

Brakes

The braking system is vital to controlling the vehicle safely, and 32 dangerous MOT fail conditions are associated with it.

These include major hydraulic leaks, worn-out brake pads beyond service limits, or brake components that are inoperative.

These faults mean your vehicle’s stopping power is significantly compromised, making it a serious road hazard.

Lamps, reflectors and electrical equipment

Effective lighting and signalling are essential for visibility and communication with other road users. There are 6 dangerous fail items in this category, including completely inoperative brake lights, headlamps, or indicator systems.

Without these, the car poses a severe risk, especially during night driving or poor weather conditions.

Nuisance

Although this might sound minor, the 3 dangerous MOT fail items listed under ‘Nuisance’ refer to excessive exhaust emissions or noise levels that breach legal limits.

These conditions may present environmental hazards or indicate deeper mechanical issues, and they render the vehicle unfit for use until fixed.

Steering

Any dangerous fault related to steering - such as excessive free play, worn-out linkages, or steering components likely to fail - poses an immediate safety risk. The MOT includes 28 dangerous fail criteria for this system.

A compromised steering system means the driver cannot adequately control the direction of the vehicle, justifying an immediate fail.

Visibility

This category relates to how well a driver can see and be seen. While it contains just 2 dangerous MOT fail items, they are serious - such as severely cracked windscreens or non-functioning wipers.

These impairments can drastically reduce a driver's field of view and reaction time, particularly in adverse weather, and must be corrected before the vehicle is roadworthy.