2025 Hyundai Ioniq 5

The ICCU failed just before the vehicle had 20k miles on it. It failed on a warm afternoon with about 77% SOC after not being charged for more than 24 hours. Immediately after starting the car with the push button ignition, I heard an audible "pop" come from the back of the passenger cabin followed up by a "Check Vehicle Electrical System" message on the dashboard. There was no warning prior to this issue and the vehicle had been driven approximately 5 miles around town about an hour earlier. I can confirm the failure was the ICCU because the 12V batter stopped receiving charge thereafter confirmed by me watching the battery voltage drop for about 10 minutes. The vehicle has not been assessed by a dealership yet as of this writing.

The ICCU went bad. I am not able to charge it at my house, because it causes the breaker to trip. It does successfully charge at a charging station. But then I learned the power could also go at any point and leave me stranded. The local Hyundai dealer (Burns Hyundai) cannot even look at my car for a month. I discovered that Hyundai has known about this issue for four years and doesn't have a real solution, just replaces the part with another of the same one. The car is not safe to drive at the moment, but I also feel like it will never be trustworthy on a longer drive as long as there's no real fix. Along with the dealer, I reported this twice to Hyundai customer service.

The emergency steering will engage at random times. The car makes a loud noise, a light on the dashboard illuminates, and the car will try to drive into another lane. This happens at least once a week, and it has never happened when there was another car around, so I wasn't about to get into a collision. It has happened when there is construction and the lane markers are unclear, when the road is a little wet and other times I can't explain. I have always been able to shove it back into the lane I want to be in, but this also seems incredibly unsafe. It could drive me into any sort of situation involving other cars or off the edge of a road. I've Googled and I am not alone in experiencing this problems. I reported this twice to Hyundai customer service.

A collision occurred when the vehicle failed to detect a stationary stop‑sign pole directly in front of it. The forward collision‑avoidance system did not provide any braking assistance or intervention before impact. The vehicle is equipped with the full safety and driver‑assistance package, including camera and radar‑based collision‑avoidance features, so the system was expected to recognize an obstacle in the vehicle’s path. The failure created a safety risk because the vehicle did not respond to an object directly ahead, and the driver relied on the advertised safety features to help prevent or mitigate such collisions.

ICCU / 12‑V failure & repair – 2025 Ioniq 5 (Illinois) Bought my 2025 Ioniq 5 new in Feb 2025. On 4/21/26, at about 8,653 miles, I suddenly got a red battery icon and “Stop vehicle and check power supply” while driving. I pulled over, limped it home, and it wouldn’t reliably go into READY. Bluelink showed DTC P1A9096 (Electric Vehicle / “Air Flap”), so I had it flat‑bedded to Happy Hyundai of Libertyville. They confirmed ICCU/12‑V system failure. On 4/29/26 they completed the fix under recall/warranty. Key detail: they installed the latest ICCU revision, part# 36401‑1XAD6. They also replaced the ICCU high‑voltage fuse and the 12‑V battery (Interstate H5).

1. The repair work was done at San Leandro Hyundai service department. I do not have the parts that were worked on. 2. Fortunately, both incidents happened when the car was parked at home. The unpredictable nature of the issue though, raises safety concerns as it's unknown when the car is going to die. 3. I have repair orders from San Leandro Hyundai service department of the error codes and repair work conducted. 4. Unknown. I assume the dealership sent the faulty ICCU back to the manufacturer. 5. For the first incident, yes, there were brief notifications on the dashboard about the battery discharging. That was happening for a couple of months prior to the car dying the first time, Feb 9, 2026. For the second incident, no there were no warning messages before the car died the second time Apr 27, 2026. SUMMARY OF INCIDENTS Incident #1 — February 2026 — ICCU failure, vehicle towed to dealer — DTC P1A9096 fault code identified — 22 days out of service — ICCU assembly and high voltage fuse (H110) replaced — 12V battery tested healthy but not replaced, despite Service Advisor Alexa's explicit assurance that replacement was standard protocol for this repair type — Rental reimbursement of $209.96 still outstanding — Maintenance warning appeared approximately one month post-repair; dismissed by resetting service clock with no diagnosis Incident #2 — Current (April 2026) — 12V battery drained to 0%, vehicle completely unresponsive, towed to dealer — Hyundai app showed 47% battery and 'all systems normal' at point of complete failure — D00 fault code identified on 12V battery; sensors reactivated and battery recharged — Traction battery range reduced approximately 50% (~150 miles vs. expected ~344 miles); attributed to battery learning reset, root cause unknown — 4 panic notifications received from Hyundai app on April 30, 2026 while vehicle is in dealer's possession — cause unknown

The contact leased a 2025 Hyundai Ioniq 5. The contact stated that while driving at 25 mph, the battery warning light, reduced power warning light, and an unknown warning light depicting a vehicle with an exclamation mark illuminated. Additionally, a "stop vehicle and check power supply" message appeared, and the vehicle lost power. The driver steered to the side of the road, and the vehicle was towed to a dealer. It was diagnosed that the ICCU unit and ICCU fuse were defective and needed replacement. The vehicle was repaired, and the manufacturer was notified of the failure. The failure occurred at approximately 82,069 miles.