Mine was "a bad injector" that ended up being a replacement of all 3 injectors on the passenger bank. Local Kia dealer set up a call with Kia Techline and made the determination on the first day. It then took them three weeks to actually get a part. During the first 2.5 of those three weeks, no one had any idea where to get the injectors or if there even were any in the US...to the degree that Kia National Customer Service told me that I should review my warranty coverage and be prepared to have the car lemon-lawed. Not exaggerating...this is what the rep I was dealing with told me. The dealership was useless - although, in their defense, they were probably getting the same runaround that I was...but they didn't do much to make us comfortable. We got a Kia K5 to drive in the interim, and I had to beg for that. "Kia doesn't 'do' loaners," as my service advisor explained it, and they would not rent us anything, despite me arguing that a 4-passenger sedan (albeit a reasonably nice one) was hardly a substitute for an 8-passenger EX trim Carnival. The whole process was...a nightmare, frankly, in terms of new car ownership. Miraculously, "the injector" showed up 3 days before week 4 started, and the dealership got everything installed quickly. Only when I picked it up did I see the paperwork, and a different service advisor confirmed that three of the six injectors had been replaced. It's been three weeks now since we collected it and the driving issues are resolved - no check engine light, no stuttering. It's been lovely to drive.