Just wanted to chime in my experience.
I have the new MHEV KIA also and I have the same problems, not even a year old and today the warning light for filter came on for the 3rd time.. First 2 times I went service and they charged me 40 euros to clear it, with the last time being exactly a month ago (1100 km) during which time most of the time spent is on highways with 90+km/h. This seems like a wide-spread problem with this line of KIAs and I would not recommend anyone to get this model of KIA until they fix this issue.
I’ll see what they say in the dealership on Monday and if nothing useful then I will try the method mentioned by gilders also.