2023 Hyundai Kona

After a routine service visit, the vehicle’s braking and speed‑control systems began to behave abnormally. The ABS/ESC control module was replaced or reprogrammed without documentation, and immediately afterward the vehicle’s braking feel, speed‑control behavior, and forward‑collision warning timing changed noticeably. These changes created a safety risk because the vehicle no longer responded in a predictable way compared to its original performance. The affected components are available for inspection upon request. The issue was reproduced multiple times under normal driving conditions. Braking response became inconsistent, and the speed‑control system no longer behaved as it did before the service. The timing and behavior of forward‑collision alerts also changed compared to pre‑service operation. These changes created unpredictability in traffic, especially during following‑distance adjustments, stop‑and‑go situations, and sudden‑braking scenarios. The dealership did not provide technical documentation or explanation for the module replacement or configuration changes and did not acknowledge the change in system behavior. The manufacturer’s customer service reviewed the case but did not provide technical findings. An independent service center could not verify the original configuration because the manufacturer did not provide the Manufacturer Build Sheet. The vehicle has not been inspected by police or insurance representatives. No warning lamps or dashboard messages appeared before or after the issue. The only indication of a problem was the sudden change in braking, speed‑control, and forward‑collision system behavior immediately after the service visit.

This has happened 3 times and I’ve only owned the car since Sept 2023, the first time was Feb 4 2024, then Feb 28th and March 11, 2024, when I am trying to accelerate I push on the gas and the rpm’s will go higher but the car doesn’t gain any speed.so when trying to pass a vehicle I can’t because it will do this and it’s dangerous, I do have a video of this

While driving on the highway on an extended trip my cruise control dropped its speed from 71 to 65 without warning. On one occasion it happened while I was in the passing lane with a lot of traffic behind me. It created a very dangerous situation before I could get into the right lane. Another incident was when again I was driving along, no one in front of me, beside me or behind me and the speed dropped once again. Had I been in traffic who knows what would have happened. I have turned the automatic breaking system off because while on a trip I was in the right lane when a car cut me off. The breaks went on and the car went totally out of control! I have filed a complaint with Hyundai and after waiting 8 weeks for a call regarding my case number they refuse to acknowledge that it is a manufacturing issue. I have had the vehicle into the dealer 3 times and they have not been able to replicate it by driving around the area, but have not taken it out on the highway at a higher speed which is when it occurs and when one would use the cruise control. I have only 9,000 miles on the car at this point and no remedy in sight.

Car stopped accelerating on the highway and held me at 40mph. This happened twice. Then before being able to get it in for service while driving the car made a loud bang and came to a rolling stop again on the highway and the transmission control system alarm went off and the car would not move. Had to get towed off the highway and in a rental now. This was a brand new 2023 hyundai kona sel limited.

The cruise control on this 2023 Kona has not worked since the day I purchased it. When the cruise control is engaged it will suddenly decelerate, but the cruise still appears engaged. It sometimes then suddenly reaccelerates. This causes traffic to suddenly back up behind me, and also to be in danger in front of me when it reaccelerates rapidly. I informed the dealer immediately of the issue. They advised there was a 2022 in their shop for the exact same issue at 8,000 miles. They asked me to bring mine in, which I have done now three times. That shop now has 4 Konas with the exact same issue, yet they do not have a fix. The Hyundai forum boards are full of this same complaint. I have contacted Hyundai Corporate. They also don’t have a solution, but won’t take back my new vehicle. I have less than 1,000 miles on this Kona - most of that from driving one hour to/from the dealer 3 times. I have been understanding and professional in my dealings with them however, I have run out of patience. I did not get what I paid for and am being asked to put myself/my family in danger driving this vehicle back and forth to this dealer who doesn’t even have a fix.

The car is set at a speed for cruise control. For no reason it loses power, after a while it returns speed as set. At the beginning the doors weren’t working for locking and unlocking by the handle. Seems okay now but I made a video showing the rear camera staying on while driving. Also included, two pictures of maintenance reports with different results.