The Hyundai-Kia ICCU saga, explained: what every E-GMP buyer should know

If you've shopped for a used Hyundai Ioniq 5, Kia EV6, Hyundai Ioniq 6 or Genesis GV60, you'll have run into four letters that generate more worry than almost anything else in the used-EV world: ICCU. It's the single component behind a string of recalls, a class-action lawsuit, and a lot of secondhand anxiety. It's also widely misunderstood, and the full picture is far less frightening, and far more manageable, than the headlines suggest. Here's what it actually is, what goes wrong, which cars are affected, and what it means if you're buying one used.

What the ICCU actually is

The Integrated Charging Control Unit is the box that manages how electricity moves around the car. Most importantly, it converts power from the big high-voltage traction battery down to the 12-volt system that runs everything else: the computers, lights, locks, screens and the contactors that physically connect the drive battery. In an old petrol car, the alternator kept the 12-volt battery topped up. In these EVs, the ICCU does that job.

When it works, you never think about it. When it fails, the knock-on effects are serious, because if the 12-volt system loses its supply, the car can't keep its low-voltage "lifeblood" alive, and eventually it can't drive.

What goes wrong

The root cause is a power transistor (a MOSFET) inside the unit that can be damaged by repeated electrical and thermal stress, often associated with fast charging over time. When it fails, it can take an associated fuse with it, and the ICCU stops charging the 12-volt battery.

In practice, owners see warnings such as a reduced-power or charging-system message, the car may drop into a "fail-safe" limp mode, and in the worst case it can lose drive power entirely. Crucially, the system is designed to give a warning with time to pull over safely before that happens, rather than cutting out instantly. The other common symptom is a car that simply won't "wake up" after sitting, looking for all the world like a flat 12-volt battery, because in effect it is, just with the ICCU as the underlying cause.

Which cars are affected, and which aren't

This is where precision matters, because the affected list is specific:

• Hyundai Ioniq 5 (2022-2024)
• Kia EV6 (2022-2024)
• Hyundai Ioniq 6 (2023-2025)
• Genesis GV60, Electrified GV70 and Electrified G80/GV80 (2023-2025)

These are the 800-volt E-GMP cars. Two important exceptions:

• The Kia EV3 is not in this group. It's a 400-volt car using different power electronics, and it isn't part of the ICCU recall. There's no systemic ICCU pattern on it.
• The newest cars use a redesigned, second-generation ICCU. The Hyundai Ioniq 9 and the refreshed Kia EV9 launched after the defect pattern emerged, with hardware revisions intended to fix it, and so far there's been no wave of complaints naming them.

In other words, this is largely a story about the first wave of E-GMP cars built between roughly 2022 and 2024, not the platform forever.

The recalls and the warranty extension

Hyundai, Kia and Genesis issued recalls (in the US, campaigns that expanded and replaced earlier ones through 2024) under which dealers update the ICCU software and, where needed, replace the ICCU and its fuse, free of charge. Cars that had earlier service-campaign work still needed the later recall fix.

On top of that, the manufacturers extended the ICCU warranty dramatically, to 15 years, with mileage caps that vary by market (around 300,000km / 186,000 miles in the UK and Europe, and 180,000 miles in the US). The extension is generally applied automatically and is the single most reassuring fact for a used buyer: even if a covered car needs ICCU work years from now, the cost should not fall on you.

The part that isn't fully resolved

Honesty matters here, because the saga isn't entirely closed. A class-action lawsuit filed in the US alleges that even the replacement ICCUs fitted under recall can still fail, with some owners reportedly having units replaced more than once. There's also genuine disagreement about how common failure really is: the manufacturers' own figure is around 1% of affected cars, while some owner-side estimates run far higher. And because demand for parts has at times outstripped supply, a failure can mean weeks off the road waiting for a replacement.

None of that means these cars are ticking time bombs, the large majority never have an ICCU problem, but it does mean the issue deserves respect rather than dismissal, and that a careful used buyer should verify rather than assume.

What it means if you're buying used

The practical takeaways are straightforward:

• Run a VIN-level recall check with the relevant manufacturer (Hyundai, Kia or Genesis), and confirm the ICCU software update and any hardware replacement have been completed. Get it in writing.
• Ask about the 12-volt battery. Many "dead" 12-volt batteries on these cars were quietly damaged by months of marginal ICCU behaviour, then failed after a software update changed how the system behaved. A car that's had a fresh 12-volt battery and the recall work is in good shape.
• Lean on the warranty extension. Confirm the specific car is covered; it transforms the ICCU from a financial risk into an inconvenience risk.
• Prefer later builds where you can. A post-update car, or one of the newer second-generation-ICCU models, carries less exposure.
• Don't let it scare you off the platform. The E-GMP cars are among the best EVs on the road: fast 800-volt charging, strong range, excellent packaging. The ICCU is a real but well-documented and now well-mitigated issue, and the steep used depreciation on these cars (a Genesis GV60 for the price of a small hatchback, for instance) is partly a reflection of fears that are, for a careful buyer, largely manageable.

The bottom line

The ICCU story is a genuine engineering stumble that the Hyundai Motor Group has been slow to fully resolve, and it's fair to be cautious. But it's also a known quantity: specific cars, a clear recall, a 15-year warranty backstop, and a redesigned part on the newest models. For a used buyer who does the checks, it's a reason to negotiate hard and verify carefully, not a reason to walk away from some of the most capable electric cars you can buy secondhand.