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.

Vehicle was service at a Hyundai Dealer for routine required maintenance to continue the warranty. Less than 24 hours later I was driving my special needs, handicap daughter to breakfast and pulled into a handicap parking space and placed my foot on the brake. The pedal seemed to not have any tension and go to the floor. The emergency collision warning went off, but the brakes did not work. The vehicle jumped over a parking curb, knocking over a handicap sign, going across the sidewalk, hitting a garbage can and finally coming to a stop in a brick building.