There is a sound that recurs across the 2024 Hyundai Ioniq 5 complaint file with unusual consistency: a loud pop from the rear of the vehicle, followed by a dashboard lighting up "like a Christmas tree," followed by a warning to stop the vehicle and a collapse into reduced-speed "turtle mode." It appears so often, in nearly identical language across unrelated owners, that it functions less like an anecdote and more like a fingerprint. The component leaving that fingerprint is the Integrated Charging Control Unit (ICCU), and its behavior is the central story of one of the most lopsided complaint files in NHTSA's electric-vehicle data.
The numbers are stark. NHTSA's complaintsByVehicle endpoint returns 211 consumer complaints against the 2024 Ioniq 5. Of those, 170 cite the electrical system — roughly four out of every five records. The next clusters, fuel/propulsion system (48 reports) and power train (36), overlap heavily with the same ICCU failure mode, because losing the unit that charges the 12-volt battery and manages the high-voltage charging path presents simultaneously as an electrical, propulsion, and powertrain fault. This is not a diffuse quality file with many small complaints. It is one problem, reported many times.
What the ICCU does — and what happens when it fails
In Hyundai's E-GMP electric platform, the ICCU is the box that converts high-voltage traction-battery power down to charge the conventional 12-volt battery, among other charging functions. The 12-volt battery, in turn, runs the low-voltage electronics that keep the car drivable. When the ICCU stops doing its job, the 12-volt battery drains, and the vehicle loses the ability to sustain drive power. NHTSA's own recall summary states the mechanism plainly: "The Integrated Charging Control Unit (ICCU) may become damaged and stop charging the 12-Volt battery, which can result in a loss of drive power." The agency's consequence statement is one sentence: "A loss of drive power increases the risk of a crash."
The owner reports put flesh on that clinical language. In a complaint filed December 28, 2025, an owner wrote: "The ICCU failed while driving. A loud pop occurred then a red warning light came up asking you to stop the vehicle and check the power supply. The car went into turtle mode where I could at best drive 25 miles per hour." Crucially, the same owner added: "This car was part of a recall last year to prevent this issue, however only a software fix was performed." Another report, filed December 31, 2025, describes the now-familiar sequence — a pop, a "stop vehicle and check power supply" warning, a second "12V battery voltage low" alert, and then a complete shutdown requiring a tow.
Why there are two recalls, not one
The recall history explains why owners are still filing these complaints after a fix was issued. Hyundai's first action, campaign 24V204000, was filed March 15, 2024, covering certain 2022-2024 Ioniq 5, 2023-2024 Ioniq 6, and related Genesis Electrified models. But that campaign was superseded. Per NHTSA's record, "This recall is replaced by NHTSA recall number 24V-868. Vehicles already repaired under this recall will need to have the new remedy completed." The replacement, campaign 24V868000, was filed November 18, 2024, and its remedy is materially different and more thorough: "Dealers will inspect and replace the ICCU and its fuse, as necessary. In addition, dealers will update the ICCU software."
That distinction — between a software-only first attempt and a hardware-replacement second attempt — is the crux of the consumer-protection story. Several complaints in the file are explicit that the initial remedy did not hold, and the supersession of 24V204000 by 24V868000 is the official acknowledgment that the first approach was insufficient on its own. For an owner, the practical implication is that a vehicle "already repaired under" the earlier recall is not actually remediated; under 24V868000, it "will need to have the new remedy completed," potentially including a physical ICCU and fuse replacement.
The 12-volt battery subplot
Layered beneath the ICCU campaigns is a related but distinct grievance that appears repeatedly in the complaint file: premature failure of the 12-volt battery itself. One owner, filing December 27, 2024, reported a "12V battery dead" at just "5 months" of ownership, with a "repeated reoccurring dead battery issue" and a dealership "asking money for replacement." Another wrote that the original-equipment 12-volt battery "fails, resulting in an emergency stop or failure to start," and that owners had resorted to buying a correct replacement battery themselves. Whether these are downstream symptoms of ICCU undercharging or a separate battery-quality issue is exactly the kind of question NHTSA's complaint data is designed to surface for the agency's investigators — and the volume here is substantial enough to warrant that scrutiny.
For the consumer, the action items are unusually clear-cut. First, an Ioniq 5 "already repaired" under the original 24V204000 software remedy is not done — owners should confirm with a dealer whether the superseding 24V868000 remedy, including any necessary ICCU and fuse replacement, has been performed. Second, the failure mode is a driving-power loss, not a no-start nuisance; a pop followed by a power-supply warning is a stop-the-vehicle event, not something to drive through. Third, owners experiencing repeated 12-volt battery deaths should document each occurrence, because the aggregate of those reports is what moves the federal needle.
The broader signal for the EV industry is that the 12-volt architecture — the humble legacy subsystem that every electric car still inherits from a century of internal-combustion design — has become a recurring single point of failure. The Ioniq 5's complaint file is the clearest public dataset showing how a single charging-control component, when it fails, can take an otherwise modern electric vehicle off the road in seconds. Two recalls deep, the reports are still coming in.