The green indicator light on the Citroen TT serves as a signal for various functions, depending on its specific application within the vehicle. Typically, a green light indicates a system that is functioning correctly or a feature that is currently engaged, such as turn signals or cruise control. This light is designed to be clearly visible without distracting the driver. If the light illuminates unexpectedly, it may indicate a fault that requires further inspection. Always consult the vehicle owner's manual for the exact meaning of the green indicator light in your vehicle.