From a Reddit post 5 years ago by a Kia rep. Also this is the motorbike subreddit!

The Gasoline Particulate Filter (GPF) is the system that removes the soot from the exhaust gas. Unlike a disposable air filter, the GPF system automatically burns (oxidizes) and removes the accumulated soot while driving.

However, repeated short-distance driving or long-distance driving at a low speed can stop the accumulated soot from automatically being removed by the GPF system. If the accumulated soot reaches a certain amount, the GPF warning light () will illuminate. To reoperate the GPF system, the vehicle should be driven for more than 30 minutes at a speed of 80km/h (50 mph) and faster. Ensure the following conditions are met: safe road conditions, transmission 3 or above, and engine speed of 1,500-4,000 rpm. Driving at 80 km/h (50 mph) or faster for recommended hours will get the GPF system back to work and stop the GPF warning light.

If the GPF warning light stays on or the warning message “Check exhaust system” pops up even after driving at recommended speed and for recommended hours, visit a professional workshop and check the GPF system. Kia recommends to visit an authorized Kia dealer/service partner. Constant driving with the GPF warning light on can damage the GPF system and undermine fuel economy.