How do car hazard warning lights work in the UK?

Car hazard warning lights (commonly called 'hazard lights' or 'double flashing lights' in the UK) are controlled by the vehicle's electronic control unit to flash simultaneously, alerting other road users to potential danger. In the UK, these are legally required safety features found in all modern vehicles including popular models like the Vauxhall Corsa, Ford Fiesta, and Nissan Qashqai. There are three main types of flasher units used in UK vehicles: 1) Capacitive flashers - use capacitor charge/discharge cycles to create the flashing pattern 2) Thermal flashers - rely on a bimetallic strip that expands/contracts with heat to make/break the circuit 3) Electronic flashers - use transistor switching for more reliable operation, commonly found in newer vehicles like the Tesla Model 3 and BMW i4. UK drivers should activate hazards when stopped due to breakdown or to warn of hazards ahead, particularly important on busy motorways like the M25 or in poor visibility conditions. The system must meet strict UK MOT testing requirements for proper operation.