Why is my car's indicator flashing fast? UK causes and fixes

A fast-flashing indicator (commonly called 'hyperflashing') in UK cars is typically caused by: 1) a faulty relay, 2) poor bulb contact, 3) a blown bulb, or 4) incorrect bulb wattage. In modern UK models like the Vauxhall Corsa or Ford Fiesta, this often indicates a bulb failure that needs immediate attention. Indicators (turn signals) are safety-critical components that use LED or halogen bulbs (not xenon as mentioned) to show turning intentions. UK law requires proper indicator use when: 1) turning left/right, 2) approaching junctions (30-100m before), 3) changing lanes, 4) overtaking, 5) roundabout navigation, and 6) pulling away. For most UK-spec vehicles, the correct bulb wattage is 21W for indicators - using incorrect bulbs can cause fast flashing. The relay is usually located in the fuse box under the bonnet or dashboard. If replacing bulbs doesn't fix the issue, have an MOT-certified technician check the relay and wiring.