2022 Hyundai Ioniq 5 Brakes Problems

I am writing to report a serious safety incident involving my 2022 Hyundai Ioniq 5 and to request a thorough investigation and guidance on next steps. On Jan. 3, 2026, at approximately 6:15 p.m. on a snowy day, we parked our car in the driveway of a weekend rental home near Lake Tahoe, CA. The driveway had a slight slope toward the house, and we backed the car down the driveway with the rear of the car facing the house. My husband turned off the car, then all five occupants exited the vehicle, closed the doors, and began unloading items from the trunk. The car began rolling backwards toward us and the house. It only stopped after pinning my husband into a snowbank created by a snowplow. The other three adults and our [XXX] niece narrowly avoided being struck. While pinned behind the vehicle, my husband had to dig out some snow to reach into his pants pocket and retrieve the key fob. I then moved the car forward a few feet to free him. Although he was pinned in the snow, my husband was (thankfully) not seriously injured. After freeing my husband, I put the car in Park and turned it off. In this model, the parking brake engages automatically; there is no separate parking brake button or lever. A few minutes later, without anyone in or near the vehicle, the car again rolled backwards down the driveway into the same snowbank. Tracks in the snow clearly indicate that the wheels rotated and the car rolled; it was not sliding on ice with the brakes applied. In other words, the parking brake and/or Park mechanism failed to hold the vehicle in place in sub freezing, snowy conditions. The temperature at this location and time was in the mid 20s °F. After returning home from our trip, we took the car to our Hyundai service center, which has performed all maintenance since we purchased it in 2022. The service center performed all standard diagnostics but was unable to replicate the failure conditions. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

When coming to a stop on a slight incline, the vehicle will come to a full and complete stop and occasionally begin to roll backwards after half a 2nd without changing brake pedal position. If the brake pedal is not push further down, the vehicle will continue to roll backwards. I have tested this on multiple IONIQ 5 models with the same result (2022 and 2023). This could cause a collision if there is another car behind the problem vehicle. No warning lamps. Both vehicles have done this since new. Nothing is wrong with either of the vehicles according to multiple dealers.

In stop and go traffic on freeway, car was moving at about 5 miles an hour but car kept moving, collision warning and automatic braking did not activate. Had to turn off car and coast to a stop. Nearly collided with vehicle in front

The IONIQ 5, like other electric vehicles, uses regenerative breaking. Regenerative breaking can be set at level 1, 2, 3, or i-pedal mode. This determines the strength in which the car will engage regenerative breaking automatically when the position of the accelerator petal is raised above the current speed. i-pedal mode is full one-pedal driving, allowing the driver to slow to a stop without use of the break pedal at all. At level 2, 3, or i-pedal, the car is capable of decelerating at a significant rate even when the driver is still pressing down on the pedal. For example, if you consider it as a percentage and take "foot off the pedal" as 0%, and "pedal pressed as far as it can go" as 100%, a driver could be traveling at 70 mph on the highway, with the pedal pressed at around 60%. The driver could then lift the pedal to only 30%, and the regenerative breaking would then slow the car to, say, 30 mph. This deceleration can be very strong when set to a high regen level. However, the break lights do not illuminate unless the driver takes their foot completely off of the accelerator. In i-pedal mode especially, it is possible to decelerate from highway speed to a near stop in only a matter of seconds, without the break lights ever activating. Other EV manufacturers illuminate the break lights based on the cars measured deceleration when using regenerative breaking, and do not have this issue. If the driver has driven other EVs in the past and prefers the one pedal driving mode, it is likely they will not even know that their break lights are not illuminating during heavy deceleration, creating a significant danger of being rear ended when driving in heavy traffic.

I parked the car end visited a store. Upon turning the car back on, the car freaked out and indicated that I needed to "Stop vehicle and check brake system." At the same time, the check engine light illuminated and the car entered limp home mode. CEL codes C164286 & C238001 appeared. The next day I brought the car to a Hyundai dealer who "fixed" the issue by removing a component that is unrelated to the braking and security systems and the car became drivable again for ~300 miles. I then went on two business trips and returned home. I drove the car and it again experienced the same error upon turning the car on. The braking system still functioned, but all electronic features were disabled by the car and braking involved a lot of force on the brake pedal to get the car to stop. For as long as I've owned the car, it has (infrequently) flashed the "Check automatic lane change system" when the car is turned on but the error goes away and doesn't return for weeks to months. The car is now back with the dealer who "fixed" the issue originally but their EV tech isn't always there to look at cars, even though the issue is not necessarily EV related as all cars (should) have brakes. Original incident: 9/8/2022, Second Occurrence: 9/30/2022