Can PSNI issue a prohibition or require defects to be fixed on a modified vehicle?

Yes. Enforcement officers can prevent continued use of a vehicle where serious roadworthiness defects make it unsafe, and defects may have to be repaired before the vehicle can lawfully continue.

For this Northern Ireland query, the practical issue is whether PSNI issue a prohibition or require defects to be fixed on a modified vehicle. Northern Ireland uses DVA vehicle-testing standards, so a modification is judged by what it does to the vehicle rather than by whether it is fashionable or sold online. The finished vehicle must remain safe, correctly constructed, roadworthy and compliant with lighting, emissions, tyres, steering, suspension, restraint and noise requirements that apply to it. Where a vehicle has been rebuilt, radically altered, kit converted or imported without normal type approval, DVA's Individual Vehicle Approval scheme may become relevant before registration.

Before spending money, check the DVA inspection item that the modification affects and tell the insurer exactly what has changed. Keep invoices, part specifications and approval information. A part being sold as “MOT friendly” or “road legal” is not proof that a particular installation on your car complies; poor fitting can turn an otherwise acceptable component into a defect. For this question specifically — “Can PSNI issue a prohibition or require defects to be fixed on a modified vehicle?” — the safest answer is the one above, based on the current Northern Ireland and UK official guidance rather than forum advice or rules written for another jurisdiction.