2025 Hyundai Ioniq 5

3/31/2025: New Vehicle leased. 11/24/2025: 12V battery failure. Battery replaced by dealership. 4/22/2026: 12v battery failure. Battery replaced by dealership. 6/7/2026: ICCU failure. Car cannot charge 12v battery. Car in “limp” mode - cannot drive faster than 40 mph while on highway. Fortunately was able get car to safe location to be towed. All three instances appear to be due to the same engineering flaw in the vehicle.

ICCU failed with a pop sound in the evening. Next morning, on my way to the dealership, car started fine, alerted me about the “check electric vehicle system”, but drove fine for about a mile. Then the car came to a crawl mode, refusing to go over 20mph and stopped completely with out any indication. Luckily, I was in a quiet neighborhood and was able to steer the car to the curb safely.

When I started the car at 10pm , a loud pop was heard and warning lights on the dashboard indicated an electrical problem. I turned off the radio and anything extra that could use up power; during the next 45 minutes I took surface streets instead of the freeway to drive 22 miles back home and speed was limited to 40 mph. The next day the same warning lights were on the dashboard and speed was limited to 20mph; car lost power after 1 block. Car was towed to the dealer, where an ICCU failure and blown fuse in the engine was diagnosed by dealership and replaced.

While attempting to operate my 2025 Hyundai Ioniq 5, the vehicle abruptly displayed a 'Check Electric Vehicle System' warning accompanied by a critical red master service light on the dashboard. A diagnostic scan via the factory Bluelink app revealed a hard fault code: DTC P1A9096 (ICCU / DC-DC Converter malfunction). This failure occurred under 7,000 miles, following a previous total 12-volt battery system failure a month prior. Driving the vehicle with this specific code puts the driver at immediate risk of 'Turtle Mode' or a sudden, total loss of motive power while in motion. Living in a mountainous region where the primary thoroughfare (Highway 17) lacks shoulders, an unexpected power failure presents an extreme, unreasonable highway safety risk to myself and surrounding traffic. The vehicle had to be flatbed-towed to a dealership for an entirely new ICCU assembly

I pulled my car out of the garage and proceeded to drive up the street. I suddenly heard a weird sound and an emergency warning appeared on my dashboard stating to check vehicle electrical system. I immediately stopped the car and returned it to the garage. Upon turning the car on a second time to check the message a second message appeared saying “stop vehicle and check power supply”. I called Hyundai for a tow truck to have the vehicle towed to the dealer. When I turned on the car to back it out of the garage it got halfway out and the entire system shut down making everything inoperable including flashing emergency lights, windows etc. there was very little time between the warning light going on and the car becoming inoperable. The dealer diagnosed a failure of the ICCU system which has been reported for several years. A quick Google search reveals that many Ionic owners have experienced this failure. I was incredibly lucky that this occurred within a block of my house. The previous night I was driving home on the LA freeways. Had this failure occurred at night on the freeway it could have been life threatening as there is very little time to get to safety and the hazard lights and all electronics become useless. The dealer said that they will be replacing the ICCU system with a better one. If that is the case then why wasn’t this car recalled and the ICCU replaced?

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.

The ICCU failed on my 2025 Ioniq 5 within 3 months of ownership and only 811 miles on it. The weather that morning was slightly chilly but not cold. I turned on the car and put it into reverse and after backing up only a couple feet, I heard a pop and the "Check Vehicle Electrical System" message and warning light came on. I had not DC fast charged the car since owning it and had only charged it on level 2 chargers at about 9.6kw to 12kw. The car was not charging the night before the issue occurred and had not been on the charger for several days previously as the battery level was around 70%. There were no issues or symptoms before prior to the failure. The car was towed to the dealership and the ICCU and high voltage were replaced under warranty. This is a major issue with the car and it keeps on happening to eGMP platform cars. The same issue happened with my 2023 Ioniq 5. Hyundai is not providing any information to consumers if they have actually identified the cause of the frequent failures or have manufactured a new part that corrects the manufacturing defect. Please direct Hyundai to issue a statement if they have found a fix or there needs to be a major recall until they identify and correct the underlying problem with the ICCU.

I was driving on a busy highway at a high but legal speed. For a few seconds the vehicle appeared to reset. I lost control and the screen went blank. It was a miracle I did not hit another vehicle. I contacted the dealer and they stated unless it was happening frequently - there is nothing they could do. I spent hours on the phone with the dealer attempting to schedule an appointment, they stated their EV person was not available. I contacted Hyundai customer service. They ignored me for months. They assigned me a contact person - but she would never return my calls. I called the main support number and started over after several months. This representative collected all my info - title, purchase receipt, etc - but then closed my case after a couple calls. They totally ignored the concern.