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Vehicle noise

There are rules every motorist must follow regarding vehicle noise and modifications that affect noise levels.

A vehicle may not be roadworthy if it doesn’t follow these rules, even if it has an MOT certificate.

Modifications to your vehicle may invalidate your insurance too.

Unnecessarily noisy vehicles can also be disruptive to residents who live near roads and other people who want to enjoy rural areas.



What the law says

There are slightly different rules regarding noise levels for different types of vehicles.

The official MOT Inspection Manuals contain the relevant rules for each type of vehicle.

The Road Vehicles Regulations Act cites the specific laws around vehicle roadworthiness. You can find the law about noise limits for different vehicle types in section K.

It specifically states that exhaust systems and silencers should be maintained in good and efficient working order and not be altered to increase noise levels. It also makes it clear that any exhaust system marked ‘not for road use’ or words to that effect is not road legal.

Invalidating your insurance

Changes to vehicle parts such as the exhaust system are considered a modification.  If you make changes to your vehicle without informing your insurance company, you may invalidate your insurance policy.  As a result, you could be prosecuted for using a vehicle without valid insurance.


How do I know if vehicle parts I’ve fitted are legal?

Any manufacturer-fitted part to a road-legal vehicle will have been checked and approved. Some aftermarket parts are sold as ‘not for road use’ or ‘for race use only’.

If you fit aftermarket parts such as a performance exhaust, you could be prosecuted if it does not carry a British Standard or EEC marking as your vehicle is no longer road legal. Having a valid MOT does not exempt you from prosecution. You can read more about these rules in the Road Vehicles Regulations Act.


What powers do police have?

Police officers must ensure vehicles are roadworthy. They have a number of powers to help them carry out their duties and enforce the law, including:

  • Police officers are authorised, under Section 67 of the Road Traffic Act 1988, to carry out roadside tests of motor vehicles.  They may require the driver to comply with reasonable instructions, and they may drive / ride the vehicle. It is an offence to obstruct an authorised examiner.
  • Section 163 Road Traffic Act 1988 states that police officers have a power to stop ANY vehicle being used on a road.
  • Section 164 Road Traffic Act 1988 states that police officers have a power to require production of a driving licence and certificate of motor insurance.  It is an offence to fail to produce these documents.