2025 Hyundai Ioniq 5 transmission problems

Filed Nov 9, 2026 · Electrical, Fuel system · CA

While driving at highway speeds on freeway, the vehicle suddenly presented warning message, "Stop vehicle and check power supply". Immediately after the warning appeared, the vehicle experienced a rapid loss of propulsion and entered a "limp mode", gradually losing power over the course of a few minutes as it limped into a safer location to wait for tow services. The sudden loss of drive power on an active freeway put the safety of myself and other motorists at risk, forcing me to navigate the vehicle off the roadway and onto a side street at an extremely low speed. The vehicle was subsequently towed to a certified Hyundai dealership. The dealership reported that the vehicle's battery was completely drained, leaving the car entirely unresponsive and unable to turn on. The dealership is currently inspecting the vehicle and has requested additional time to diagnose the root cause. The vehicle and its components are available for inspection.

Filed Sep 19, 2026 · Electrical, Transmission · CO

I am writing to document my case regarding my leased 2025 Hyundai Ioniq 5 XRT. Vehicle: 2025 Ioniq 5 XRT, VIN [XXX] Lease start / delivery date: Odometer: 4,368 miles Servicing dealer: Stevinson Hyundai, [XXX] Case number: XXX What happened: On Saturday, XXX, while I was driving, the vehicle displayed "Stop vehicle and check power supply" with the red 12V battery warning and the master warning light, and power was limited to approximately 25 mph. The high-voltage battery was at 66 percent. I was able to get the vehicle home at reduced speed, and Hyundai Roadside Assistance towed it to the dealer the same day. The symptoms are consistent with an ICCU failure, pending the dealer's diagnosis. Photos of the instrument cluster are attached. I consider a sudden loss of drive power at 4,368 miles to be a safety-related defect, and I have reported it to the federal safety agency. My situation: This is one of two vehicles in our household, and both of us need to get to work. The dealer is about 30 miles from my home. I am without transportation as of September 19. What I am requesting: 1. Written authorization for a rental vehicle starting immediately and continuing until my vehicle is repaired and returned, including the approved daily rate and how billing or reimbursement will work. 2. A parts availability check and estimated repair date as soon as the dealer confirms the diagnosis. 3. If the vehicle is out of service for an extended period, reimbursement of my lease payments for the time I cannot use it. 4. Confirmation of the warranty coverage that applies to the ICCU on this VIN, including any extended ICCU coverage. I am keeping a record of the days the vehicle is out of service, starting XXX. Please reply in writing so I have everything documented. Thank you for your help, [XXX] [XXX] [XXX] [XXX] INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Filed Aug 12, 2026 · Electrical, Transmission · NC

I started the car and got the warning "check electric vehicle system." The car then lost power. It would only go 27mph with the accelerator pedal pushed all the way to the floor. My safety was at risk because my car was not responding appropriately to driver input. The car is at the dealership as it is undriveable in this condition. This is the second incident with this vehicle within 6 months.

Filed Jul 11, 2026 · Transmission · CA · crash

I was slowing down, actively pressing the brake pedal to bring the vehicle to a full stop. As the car decelerated to what my senses and perception registered as a full stop, I pressed the “P” (Park) button while keeping my foot on the brake pedal. I felt the physical click of the “P” button under my thumb while still holding the brake, and my mind registered that the vehicle had successfully transitioned into Park. Before turning around, I visually confirmed that the vehicle had come to a complete stop. Believing it was fully secured in Park, I turned my head to check on my child in the back seat and naturally released the brake pedal completely. However, the system had actually rejected my command. I assume that the vehicle likely still had a small amount of speed at the exact millisecond I pressed the button, and the computer automatically blocked the “Park” command and kept the car in gear. Because an electric vehicle operates in almost complete silence, with no engine noise or vibration to indicate that it is still in gear, there was no auditory or physical cue to alert me that the car was moving when I released the brake. While my attention was turned toward the back seat for a few seconds, the car quietly began to creep forward, leading directly to the collision with the car in front of me. Following the accident, I found that the vehicle produces slightly different sounds when Park is rejected and when it is successfully engaged. However, the owner’s manual describes only the dashboard message and does not describe these sounds or explain how to distinguish them, so their meanings may be learned only through the failure. At the time of the incident, I was not familiar with the distinction between these two sounds. Because my brain processed the physical press of the button as a successful action, and I had visually confirmed that we were not moving, my focus immediately shifted to my child. I was entirely misled by the digital interface.

Filed Jul 9, 2026 · Electrical, Transmission · CA

During a family road trip, my 2025 Hyundai Ioniq 5 (~9,000 miles, less than one year old) suddenly showed red "Check Electric Vehicle System" and 12V battery warning lights and then completely lost power. The 12V system failed entirely - the vehicle could not be driven or shifted, and the doors and the rear hatch could not be locked or unlocked. It had to be flat-bedded to a Hyundai dealer because it was completely inoperable. The dealer diagnosed a failed ICCU (Integrated Charging Control Unit) and a blown ICCU safety fuse (fault code P1A9096) and is replacing both under warranty; the component is available for inspection. The ICCU converts high-voltage battery power to charge the 12V system; when it fails, the vehicle loses all electrical power and drive capability. The warning lamps appeared immediately before total power loss, with no prior symptoms at the last scheduled service. This is a known, safety-critical failure on this platform: a sudden, complete loss of power can strand occupants and, if it occurs while driving, cause loss of motive power - a serious crash risk. My vehicle was stationary when it failed, but the same failure at speed would be extremely dangerous. I have video evidence of the car completely bricked out.

Filed May 30, 2026 · Electrical, Fuel system · MA

Vehicle was parked in closed garage overnight. In the morning I tried to start the car and it was unresponsive. key fobs, digital keys, NFC cards none of them were able to open the car. Used a physical key to open the door, and then tried to turn the car on, nothing worked all screens remained black and car was unresponsive. AAA confirmed that the 12V battery was fully dead. When they jumped the vehicle we heard a pop in the car, which is a known ICCU failure indication. The car still turned on and was drivable. I got it to the dealership safely and they confirmed that the 12V battery was fully dead and car only turns in if jumped. They also confirmed that the ICCU had a failure as well and they are going to need to replace the entire battery pack/ICCU assembly.

Filed Apr 15, 2026 · Electrical, Fuel system · GA

Car charged as scheduled overnight 3/28/26 but was dead the morning of 3/29/26 and when it was jumped gave error "Battery overheated, please stop and exit vehicle" and "check electrical system" - vehicle has been in shop for 16 days, no diagnosis except that it "probably" needs a HV battery.

Filed Apr 3, 2026 · Electrical, Transmission · CA

On April 1, 2026, my 2025 Hyundai IONIQ 5 experienced a cascading electrical failure. The vehicle first displayed a warning about a problem with the on-board charger, followed shortly by an alarm and the 'Stop Vehicle and Check Power Supply' warning with a red 12V battery indicator, rendering the vehicle unsafe to drive. Had I been on the freeway this would have been extremely dangerous. My Bluelink diagnostics history confirms three fault codes from that date: P1A9096 (ICCU fault, Electric Vehicle / Air Flap system, still Open as of 4/3/2026), and P056216 (Voltage Regulation fault, Hybrid Control system, reported twice), consistent with a cascading ICCU failure causing 12V system collapse.

Filed Mar 21, 2026 · Electrical, Fuel system · AZ

Car showed electrical problem on the dash. Car would not start.

Filed Mar 20, 2026 · Acceleration, Electrical · NJ

ICCU unit of the car short circuited right in middle of driving and caused the car to go in "limp mode". Sudden pop noise and slowdown created situation where car could be rear-ended. The part has already caused recall for prior model years, but model year for my car is not included in the recall. Based on internet search it is a continued and widely prevalent issue, manufacture has not done enough to fix this and a recall needs to add new model years. Additionally, the parts are backordered and there is no immediate fix.