2025 Hyundai Ioniq 5

While charging the vehicle, we heard a loud pop. After starting the vehicle there was a warning to check the electric vehicle system. The car max speed was limited to about 20mph while driving home (it was night and the dealership was closed). The following morning while driving the car to the dealership, a new warning came on to stop the vehicle. A few minutes later, a new light came on showing a turtle icon and the car would only go about 3-4 mph. I barely made it through the busy intersection and was able to pull over before the car completely died. At that point, nothing worked: no electronic locks, no hazard lights, or other safety measures. The car was towed to the dealership (1/2 mile away) where it was diagnosed with an ICCU and fuse failure. Due to a part being backordered, the car sat at the dealership for 86 days before being fixed and returned.

I started driving and pulled out of a parking lot onto a busy road. The ICCU had failed unknownst to me and as I was underway the car started losing power and the dashboard lit up with warnings about the electrical system. I was limited to 25 MPH for a brief time and struggled to turn off into a parking lot amongst much faster traffic. While doing this the car slowed further to 10 MPH. I limped at this speed into the parking lot at which point it turned off and lot all power. This happened over the course of about 30 seconds. If it had happened on a busier road I would have been in trouble. On the highway and it would have been extremely dangerous. It was dangerous enough as is with cars passing me 20+ MPH faster than my car could go. This all occurred with no warning, and is due to an issue with the ICCU in the car that Hyundai has known about for years and has refused to address or fix.

My 2025 Hyundai Ioniq 5 has experienced repeated catastrophic 12-volt battery failures following an ICCU (Integrated Charging Control Unit) failure in November 2025. The ICCU failure caused the vehicle to lose power in traffic and required towing. The ICCU was replaced but the 12-volt battery was not replaced. Since that repair, the vehicle has experienced repeated electrical failures. The 12-volt battery dropped to approximately 3.5 volts on one occasion and approximately 1.72 volts on another. These voltages were measured and documented on video using multiple multimeters before any jump start or charging. At these voltage levels the vehicle cannot unlock doors, power systems, or operate normally. The vehicle required towing by AAA. The dealership has repeatedly recharged the battery before testing and then claimed the battery “tests good,” refusing to replace it under warranty. Numerous owners online report similar failures where ICCU problems lead to repeated 12-volt battery collapse and vehicle immobilization. Because loss of 12-volt power can disable critical vehicle systems and leave the vehicle stranded or stopped in traffic, I believe this represents a potential safety defect. I don't have the repair reports from the dealer scanned in but I can if you want them. ICCU is known failure and recall but for some reason our car doesn't appear on any recall list. 12V battery that drops below 6V is deemed unsafe and bad and 3 times (including this time) it's been below 6v but they don't believe it's a bad battery.

While traveling at highway speeds, the vehicle suffered a catastrophic and sudden loss of motive power. This resulted in a dangerous situation with no immediate ability to maintain speed in traffic. The manufacturer (Hyundai) identified a failure in the Integrated Charging Control Unit (ICCU). Despite a formal 'Notice to Cure,' the manufacturer refused to replace the 12V battery which was stressed during the failure, potentially leading to a repeat high-speed power loss event. This is a known issue with the E-GMP platform (Ioniq 5) that poses a significant unreasonable risk to public safety.

The vehicle exhibited charging failures on multiple occasions over the course of several days after being connected to a Level 2 home charging unit overnight. On repeated mornings, the high-voltage battery was found to have not charged. The vehicle also exhibited intermittent slow charging behavior during this same period. Approximately six months prior to the charging failures, the 12-volt auxiliary battery was found to be completely discharged. During this same period, the vehicle was started on one occasion to find that every warning and alarm indicator on the dashboard had triggered simultaneously. The vehicle was completely inoperable at that time. After several minutes, all warning indicators cleared and normal operation resumed without any intervention. The vehicle was brought to an authorized Hyundai dealership on March 6, 2026, where the technician diagnosed the root cause as a failed Integrated Charging Control Unit (ICCU). The ICCU is responsible for managing both high-voltage battery charging and maintaining the 12-volt auxiliary battery; a failure of this component can result in loss of charging capability, auxiliary battery drain, and potentially a complete and sudden loss of vehicle operability. As of the date of this report, the vehicle is awaiting parts with an estimated repair time of approximately one week. The repair is expected to be covered under the manufacturer's warranty. This failure occurred with fewer than 10,000 miles on a 2025 model year vehicle. Based on publicly available owner reports and online forums, ICCU failures appear to be a recurring issue across multiple Hyundai IONIQ model variants.