2021 Kia Sedona

We purchased a brand-new 2021 Kia Sedona in 2021. Since January, we’ve been experiencing an intermittent but serious issue where the vehicle refuses to accelerate or shift beyond a certain point. This issue has put us in dangerous situations multiple times. One incident occurred while crossing a fast-moving, single-lane road—our vehicle would not accelerate to the appropriate speed, placing us at serious risk. On another occasion, while merging onto a highway, the car failed to accelerate, and we feared being rear-ended due to our inability to keep up with traffic. There are no warning lights or error messages to indicate a problem when this occurs. The only temporary solution has been to pull over, turn the car off, and restart it. After doing this, the vehicle functions normally for a few days, weeks, or even months before the issue reoccurs. We have taken the vehicle to our local Kia dealership, but they were unable to replicate the problem or identify any issues. We also brought it to a second Kia dealership with the same result—no diagnosis and no resolution. We are extremely concerned for our safety and would appreciate guidance on how to escalate this issue or pursue a resolution. I also have a video of an incident.