2025 Hyundai Ioniq 5

At power-on, the car's diagnostics alerted with DTC code P1A9096, indicating a failure of the Low voltage DC-DC converter / ICCU. Vehicle was parked at home at the time, but there is the distinct possibility of being stranted at an outstation or outside cellular / tow coverage. Vehicle was towed to an authorized service center for warranty repairs (the car is ~5 months from date of purchase)

The electrical system failed while driving and I could not accelerate more than 25 mph with two children in the car. The error message said stop car and evaluate power supply. My safety and my children's safety were put at risk as I was driving on a highway and could no longer accelerate above 25mph. Yes the problem was reproduced. Manufacturer is inspecting now. There was a warning light that appeared only while driving and when the initial probably began. The dealer told me this is ICCU failure, this is happening frequently, there is no timetable to get a replacement.

Received the following warning while driving my 2025 Hyundai Ioniq 5 SEL on the highway on X-mas night: "Battery Overheated! Pull over safely and leave the vehicle." Within a few miles, was able to pull over at the nearest exit and park the car off the highway. Then turned the car back on to see if the error message was still present and drove another mile, only to get the same error message. As soon as I pulled into an empty parking lot, the car lost power and was not functioning (ie unable to accelerate). I received a further "Battery Management System" error in the Vehicle Diagnostics dashboard. It was raining outside so was very uneasy that I was prompted to leave the vehicle with two young kids in the backseat. We took an Uber home which was a couple miles away from the parking lot where my stranded car was located. I had the vehicle towed to Hyundai San Leandro on 12/26/25, it was inspected on 12/30/25, and was notified by the dealership service center on 1/2/26 that the ICCU may need to be replaced to resolve the issue. They did not confirm whether they were able to reproduce the issue but I see two DTC error messages in my Hyundai app (DTC P1B9700 and DTC POA9B11). It was indicated that an ICCU was ordered which should arrive by 1/8-1/9 (3-4 days from 1/2) . If swapping in a new ICCU doesn't resolve the issue, then it was indicated that I may need a new BMS module. I was given the option to get a rental car from Enterprise (as early as the weekend of 1/3-1/4) and get reimbursed later or a loaner vehicle could be provided (if available) by the dealership sometime during the week of 1/5.

On December 26, 2025 (six months after leasing this new vehicle) the ICCU unit failed. The mileage is 5,555. This known defect poses serious safety risks as it causes the vehicle to be unexpectedly and immediately disabled. It can drive at only very slow speeds. Drivers must find a safe place as soon as possible to park and call for a tow. Specifically, I was leaving a parking lot and heard a loud pop from behind me. the dashboard immediately displayed a red warning to check the electrical system (which is the drive system in a BEV). Fortunately, I was able to back up back into the parking lot, park and call for assistance. Had I been travelling at highway speeds, it would have been much more dangerous. There was absolutely no warning that this failure was going to happen, so it can occur at any time and any place. The weather was cold and humid. It was raining at the time. This is a known issue that has affected all model years, 2022-2026, of the Ioniq 5. The dealer where I had the car towed confirmed that the ICCU unit and fuse have to be replaced. We are currently awaiting the parts delivery so the replacement can occur. The parts will be the same as those that failed (and have failed for the last five years in multiple Hyundai/Kia EV models), so I can never be sure that this will not reoccur in the future at a time/place that will pose a greater risk to our safety. The manufacturer needs to fix this known defect.

My issue seems to be the ongoing failure of the ICCU ( Integrated Charging Control Unit ) in the Ioniq 5 vehicles. I heard the "pop" sound from the back seat area while driving. The dashboard immediately started displaying "check vehicle electrical system" errors, as well as "there may be a problem with the on-board charger" The Hyundai diagnostics code refers to is P1A9096 which, from what I've found, refers to the ICCU failing which leads to the 12v battery failing.

I had driven a few miles to a store and was inside for about 10 minutes. I went out to the parking lot and started the car by pressing the button. Within the first couple of seconds after starting, there was a loud pop sound, followed by alerts on the dashboard. Checking the onboard diagnostics, I saw an alert that the charging system had a fault. Using the MyHyundai app, I saw a diagnostic code of P1A9096. I was able to drive home (albeit limited to about 40 MPH on a road with a 50 MPH speed limit and traffic that drives faster than that) and park. Testing it later that night, I was able to start it, but soon after, there was a loud beeping sound and bright red alert on the dash warning me that I should "Stop vehicle and check power supply." The next morning, when trying to get it on the flatbed tow truck, the vehicle started, but when I tried to adjust the seat for the tow truck driver, it went entirely dead. The driver jumpstarted it, but it was difficult to get the car into gear to move it on the flatbed. Around this time, I noticed that the phone was showing two new diagnostic entries, both with code P056216. We eventually got it into gear and onto the truck, and then delivered to the dealer, where it is currently awaiting diagnostics. There was no obvious safety issue while I was driving, though I worry now that if I had tried to use the 12V system while I was driving, then the entire system might have failed while in motion.