2026 Hyundai Ioniq 9 Fuel system Problems

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 ID

11757960

Incident

Aug 4, 2026

On XXX I had two warnings pop up on the car to check electric vehicle system while driving. The car was still driving fine, so I took it into the dealer (ALM Hyundai in [XXX]) within a few days to have general maintenance and for the DTCs to be reviewed. The EV tech was 2 weeks out, so they just briefly reviewed the code and said it was safe to drive. Everything was fine until XXX. I fully charged the vehicle overnight on XXX. Around 11:30 a.m. on XXX I went to drive the car. This was the 3rd time I had driven it since charging it and was about 2 minutes into the drive when the check electric vehicle system light came on again and the car started losing power and accelerating on its own. It cycled this way at a few times and I quickly pulled over into a parking lot as the car was crawling. I turned the car off and back on and returned to my office. I was not able to get it towed to the Hyundai dealership until XXX. When I turned the car on in the morning of XXX, the light had disappeared and I never received an alert within the app that the code appeared in the car. Thankfully my young children were not in the car with me at the time and I was not on a highway or this could have been a serious accident. The car is still within diagnostics, but the last update that I received on XXX the service department stated that they had not been able to duplicate the issue or code. When I dropped the car off, they told me that they could not repair it if they could not duplicate the code. If they cannot find an issue and the fact that the car did not record the code makes this a serious safety hazard not only to anyone driving the vehicle, but other vehicles on the around driving around it. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA ID

11757195

Incident

Aug 11, 2026

On 8/3/26 my Ioniq 9 had a warning message to Check the Electrical System, but provided no additional information. I was able to drive the car home, anticipating that I be able to take it in to the Hyundai dealer where i purchased the vehicle. It should be noted that the car went into limp mode (max 25 mph) for the final six miles to my home. I researched the issue on line and determined that it was possible to get the car to the dealer based upon the experience of other Hyundai owners. Note: There was no information in Hyundai documentation as to the range i could expect once receiving the error message. The morning that I took the car to the dealer, the car started normally but within 1/2 mile it went into limp mode again and within 100 feet went into 'turtle mode" 2-3 mph and came to an abrupt stop. I was at the side of the road and put the hazardous flashers on (which remained on for only a matter of minutes before going dead). The vehicle was then totally dead with no emergency flashers on a busy street). I had the vehicle towed to the dealer which was returned later in the day noting that "the 12 v battery had been recharged and subjected to load and GDS diagnostics, both passed. ICCU inspection confirmed no faults, no parasitic current draw detected, ECR reset performed". Got the car home and the very next morning received a code indicating that electrical service was required. Took the car back into the dealer and have just been informed that the ICCU is being replaced. Safety concerns: lack of documentation and information from mfr, a dead vehicle on a well-travelled road with no functioning safety hazard flashers. Luckily the event occurred during daylight hours and not during the nighttime hours.

NHTSA ID

11755299

Incident

Aug 3, 2026

On XXX, at approximately 2:20 PM, while driving about 30 mph on a suburban road in [XXX], a red battery warning light appeared on the main instrument cluster. I pulled over and contacted Hyundai support. When I attempted to resume driving, the vehicle accelerated sluggishly with noticeably reduced power. I pulled over a second time and parked with the vehicle still powered on. While I was on the phone with Hyundai roadside assistance, a red ‘Stop vehicle and check power supply’ warning message appeared on the dash, and the vehicle completely lost power several minutes later, becoming inoperable. It had to be towed to a Hyundai dealership. Weather was clear and road conditions were normal. There was no crash, fire, or injury. The vehicle had approximately 3,770 miles at the time of failure. As of this report, the dealer has not yet completed diagnosis. The symptoms are consistent with the integrated charging control unit (ICCU) failure pattern widely reported in Hyundai EVs, but this has not yet been confirmed. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA ID

11743940

Incident

Jun 13, 2026

The Integrated Charging Control Unit (ICCU) on this vehicle produces loud whirring noises when charging at 80% or above. This has been documented in writing to the service department. The ICCU defect is a known systemic issue across the Hyundai and Kia EV platform. The vehicle is currently scheduled to return to the dealer for this and other defects. This is the second major service visit on a vehicle leased in March 2026 that was already out of service 28 consecutive days for a sunroof failure.

NHTSA ID

11741651

Incident

May 22, 2026

Failure of the ICCU during normal driving conditions. The vehicle was controllable, and driver was able to bring the vehicle to a safe location as vehicle performance deteriorated. The failure left the driver and passenger without power during a storm in an unfamiliar area. After about 45 minutes of waiting for roadside assistance, the vehicle lost all auxiliary power and no functions were available (including lights and door lock controls). Vehicle was towed to a local dealership, where issue was diagnosed and part has been replaced. The failure was not preceded by any significant event. Warnings present on the driver's information panel while driving.

NHTSA ID

11730311

Incident

Apr 1, 2026

Suspected ICCU failure. Progressed rapidly to car being immobile. Known issue not being addressed by Hyundai.

NHTSA ID

11726175

Incident

Mar 22, 2026

The vehicle was being driven on a city street when it suddenly felt sluggish and lost acceleration ability. It would not drive above 43mph in a 50mph zone. The display showed the error "Check electrical vehicle system". After getting home a mile away and turning it on, driving was tested again after about 30 minutes. Upon entering drive mode, it beeps rapidly and displayed "Stop vehicle and check power supply". Battery would not charge, with the vehicle announcing "Charge unsuccessful". The Hyundai app shows an ELECTRIC VEHICLE DTC P1A9096 and DTC Sub System: Air Flap (which appears to be incorrect since the air flap is functional and it's an ICCU failure). The dealer inspected and diagnosed the issue as an ICCU failure, requiring a new ICCU and fuses. Parts are on backorder with availability unknown.

NHTSA ID

11722307

Incident

Feb 28, 2026

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 ID

11705434

Incident

Dec 14, 2025