2026 Hyundai Ioniq 9 driver assist problems

FORWARD COLLISION AVOIDANCE: ADAPTIVE CRUISE CONTROL

I am reporting serious repeated safety failures with my 2026 Hyundai IONIQ 9 involving unintended emergency braking and sudden loss of propulsion. While traveling approximately 70–75 mph northbound on I-15, the vehicle suddenly displayed an emergency braking warning and aggressively slowed despite no apparent obstacle or traffic condition requiring emergency braking. Before I could regain control, the vehicle came to a complete stop in active freeway traffic with vehicles around and behind me, creating an extreme risk of a high-speed rear-end collision. Something similar has happened on two other occasions. On a separate occasion while traveling on I-40, the vehicle again unexpectedly initiated emergency braking. I was able to disengage adaptive cruise control and regain control before the vehicle came to a complete stop. The vehicle has also experienced two separate loss-of-propulsion incidents. During one, the vehicle suddenly limited its maximum speed to approximately 22 mph and would not accelerate normally for approximately four miles before returning to normal operation without explanation. During another incident, the vehicle suddenly would not exceed approximately 40 mph. I safely pulled over, but once stopped the vehicle would not accelerate from 0 mph, leaving me unable to re-enter traffic. Normal operation returned only after shutting the vehicle off and restarting it. The Hyundai dealership has inspected the vehicle 3 times and has had it for more than 3 weeks, but states it cannot replicate the conditions. These failures are intermittent but have occurred repeatedly and involve critical braking and propulsion systems. I am concerned another event could cause serious injury or death, particularly if the vehicle brakes unexpectedly at freeway speed or loses propulsion while merging or crossing traffic. I am requesting NHTSA investigate this potential safety defect.

NHTSA complaint #11757960 — an unverified report by a vehicle owner.

FORWARD COLLISION AVOIDANCE: AUTOMATIC EMERGENCY BRAKING

I am reporting serious repeated safety failures with my 2026 Hyundai IONIQ 9 involving unintended emergency braking and sudden loss of propulsion. While traveling approximately 70–75 mph northbound on I-15, the vehicle suddenly displayed an emergency braking warning and aggressively slowed despite no apparent obstacle or traffic condition requiring emergency braking. Before I could regain control, the vehicle came to a complete stop in active freeway traffic with vehicles around and behind me, creating an extreme risk of a high-speed rear-end collision. Something similar has happened on two other occasions. On a separate occasion while traveling on I-40, the vehicle again unexpectedly initiated emergency braking. I was able to disengage adaptive cruise control and regain control before the vehicle came to a complete stop. The vehicle has also experienced two separate loss-of-propulsion incidents. During one, the vehicle suddenly limited its maximum speed to approximately 22 mph and would not accelerate normally for approximately four miles before returning to normal operation without explanation. During another incident, the vehicle suddenly would not exceed approximately 40 mph. I safely pulled over, but once stopped the vehicle would not accelerate from 0 mph, leaving me unable to re-enter traffic. Normal operation returned only after shutting the vehicle off and restarting it. The Hyundai dealership has inspected the vehicle 3 times and has had it for more than 3 weeks, but states it cannot replicate the conditions. These failures are intermittent but have occurred repeatedly and involve critical braking and propulsion systems. I am concerned another event could cause serious injury or death, particularly if the vehicle brakes unexpectedly at freeway speed or loses propulsion while merging or crossing traffic. I am requesting NHTSA investigate this potential safety defect.

NHTSA complaint #11757960 — an unverified report by a vehicle owner.

FORWARD COLLISION AVOIDANCE: WARNINGS

I was driving at 35 mph speed on a straight road and the car automatically activated emergency steering and pushed towards right I had to jerk the steering towards left to prevent any accidents. No adverse event occurred however this was unnerving experience.

NHTSA complaint #11745480 — an unverified report by a vehicle owner.

FORWARD COLLISION AVOIDANCE: WARNINGS

On May 14, 2026, while traveling at highway speed in a clear passing lane with no obstacles present, the autonomous emergency braking system activated without cause and brought the vehicle to a complete stop. A following vehicle nearly rear-ended me. I recorded a voice memo immediately after the incident. A third-party crash detection application on my phone independently logged the hard stop event. A second phantom braking incident has since occurred. The vehicle is a 2026 IONIQ 9 Calligraphy leased in March 2026. This is the second major defect event on this vehicle, which was also out of service 28 consecutive days for a sunroof failure earlier this year. I am aware of ICCU-related systemic defects documented across the Hyundai and Kia EV platform and believe this may be connected.

NHTSA complaint #11741650 — an unverified report by a vehicle owner.

FORWARD COLLISION AVOIDANCE: AUTOMATIC EMERGENCY BRAKING

On April 23, 2026, while driving my 2026 Hyundai Ioniq 9 , the Automatic Emergency Braking system completely failed to detect an oncoming hazard. The system did not alert me, did not activate, and did not apply emergency braking. I nearly collided with another vehicle as a direct result of this failure. The vehicle has a persistent diagnostic trouble code C28AB87 — CAN time-out for the front radar unit — which disables critical Advanced Driver Assistance Systems including Automatic Emergency Braking, collision avoidance, and Smart/Adaptive Cruise Control. This is the same defect that has been present since early in my lease. The vehicle has been presented for repair at two different Hyundai dealerships on three separate occasions: Attempt 1 — Oxmoor Hyundai, [XXX] , March 19-20, 2026. Defect diagnosed, unable to repair. Attempt 2 — Oxmoor Hyundai, [XXX] , April 1-17, 2026. Front radar unit replaced. Defect remained. Attempt 3 — [XXX] Hyundai, [XXX] , April 23, 2026 to present. Suspected bad connector, part ordered. Vehicle still at dealership. Cumulative days out of service: 24 days and continuing for the same safety defect. I have formally demanded a buyback from Hyundai Motor America under Ohio Lemon Law ORC 1345.72. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA complaint #11735039 — an unverified report by a vehicle owner.

FORWARD COLLISION AVOIDANCE: WARNINGS

On April 23, 2026, while driving my 2026 Hyundai Ioniq 9 , the Automatic Emergency Braking system completely failed to detect an oncoming hazard. The system did not alert me, did not activate, and did not apply emergency braking. I nearly collided with another vehicle as a direct result of this failure. The vehicle has a persistent diagnostic trouble code C28AB87 — CAN time-out for the front radar unit — which disables critical Advanced Driver Assistance Systems including Automatic Emergency Braking, collision avoidance, and Smart/Adaptive Cruise Control. This is the same defect that has been present since early in my lease. The vehicle has been presented for repair at two different Hyundai dealerships on three separate occasions: Attempt 1 — Oxmoor Hyundai, [XXX] , March 19-20, 2026. Defect diagnosed, unable to repair. Attempt 2 — Oxmoor Hyundai, [XXX] , April 1-17, 2026. Front radar unit replaced. Defect remained. Attempt 3 — [XXX] Hyundai, [XXX] , April 23, 2026 to present. Suspected bad connector, part ordered. Vehicle still at dealership. Cumulative days out of service: 24 days and continuing for the same safety defect. I have formally demanded a buyback from Hyundai Motor America under Ohio Lemon Law ORC 1345.72. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA complaint #11735039 — an unverified report by a vehicle owner.

FORWARD COLLISION AVOIDANCE: ADAPTIVE CRUISE CONTROL

On April 23, 2026, while driving my 2026 Hyundai Ioniq 9 , the Automatic Emergency Braking system completely failed to detect an oncoming hazard. The system did not alert me, did not activate, and did not apply emergency braking. I nearly collided with another vehicle as a direct result of this failure. The vehicle has a persistent diagnostic trouble code C28AB87 — CAN time-out for the front radar unit — which disables critical Advanced Driver Assistance Systems including Automatic Emergency Braking, collision avoidance, and Smart/Adaptive Cruise Control. This is the same defect that has been present since early in my lease. The vehicle has been presented for repair at two different Hyundai dealerships on three separate occasions: Attempt 1 — Oxmoor Hyundai, [XXX] , March 19-20, 2026. Defect diagnosed, unable to repair. Attempt 2 — Oxmoor Hyundai, [XXX] , April 1-17, 2026. Front radar unit replaced. Defect remained. Attempt 3 — [XXX] Hyundai, [XXX] , April 23, 2026 to present. Suspected bad connector, part ordered. Vehicle still at dealership. Cumulative days out of service: 24 days and continuing for the same safety defect. I have formally demanded a buyback from Hyundai Motor America under Ohio Lemon Law ORC 1345.72. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA complaint #11735039 — an unverified report by a vehicle owner.

LANE DEPARTURE: ASSIST

While driving on the freeway utilizing Highway Drive Assist, I suddenly received a warning on the heads up display stating that assisted systems were unavailable, at which point the Adaptive Cruise Control & Lake Keep Assist both deactivated. I pressed the button on the steering wheel to reactive the system and received "conditions not met" error. At this point, I placed my foot on the accelerator and it was completely unresponsive. I stabbed at hte accelerator as well as held it down without issue. Regenerative breaking also did not reactive. Fortunately, I had enough momentum to change lanes safely to the shoulder and power cycle the car. I took the car to my local dealership who did a brief test drive and could not recreate, returning the car to me without contacting Hyundai proper, and recommending I call them directly myself.

NHTSA complaint #11705434 — an unverified report by a vehicle owner.

FORWARD COLLISION AVOIDANCE: ADAPTIVE CRUISE CONTROL

Occasionally while driving my IONIQ 9 in sunny conditions with glasses on while utilizing Lane Keep Assist and the Adaptive Cruise Control system the car flashes a Warning about keeping your attention on the road, and then continues on beeping and chiming before ultimately completely stopping in the middle of the road unless you disengage the Lane Keeping Assist and Adaptive Cruise Control. I believe the sensors on top of the Steering Wheel aren’t calibrated that great for people who wear glasses, as this issue does not occur when I take my glasses off. I am not in any way obstructing the sensors, and in all cases when this has occurred, my attention is on driving and the fact that the vehicle begins to decelerate into a complete stop while in the middle of traffic is terrifying. This has happened to me about 3 times now since getting the car and all 3 times it was while I was wearing my regular glasses. When I have my sunglasses on I haven’t experienced the issue.

NHTSA complaint #11689514 — an unverified report by a vehicle owner.

LANE DEPARTURE: ASSIST

Occasionally while driving my IONIQ 9 in sunny conditions with glasses on while utilizing Lane Keep Assist and the Adaptive Cruise Control system the car flashes a Warning about keeping your attention on the road, and then continues on beeping and chiming before ultimately completely stopping in the middle of the road unless you disengage the Lane Keeping Assist and Adaptive Cruise Control. I believe the sensors on top of the Steering Wheel aren’t calibrated that great for people who wear glasses, as this issue does not occur when I take my glasses off. I am not in any way obstructing the sensors, and in all cases when this has occurred, my attention is on driving and the fact that the vehicle begins to decelerate into a complete stop while in the middle of traffic is terrifying. This has happened to me about 3 times now since getting the car and all 3 times it was while I was wearing my regular glasses. When I have my sunglasses on I haven’t experienced the issue.

NHTSA complaint #11689514 — an unverified report by a vehicle owner.

FORWARD COLLISION AVOIDANCE: AUTOMATIC EMERGENCY BRAKING

Occasionally while driving my IONIQ 9 in sunny conditions with glasses on while utilizing Lane Keep Assist and the Adaptive Cruise Control system the car flashes a Warning about keeping your attention on the road, and then continues on beeping and chiming before ultimately completely stopping in the middle of the road unless you disengage the Lane Keeping Assist and Adaptive Cruise Control. I believe the sensors on top of the Steering Wheel aren’t calibrated that great for people who wear glasses, as this issue does not occur when I take my glasses off. I am not in any way obstructing the sensors, and in all cases when this has occurred, my attention is on driving and the fact that the vehicle begins to decelerate into a complete stop while in the middle of traffic is terrifying. This has happened to me about 3 times now since getting the car and all 3 times it was while I was wearing my regular glasses. When I have my sunglasses on I haven’t experienced the issue.

NHTSA complaint #11689514 — an unverified report by a vehicle owner.