Why does my Hyundai Ioniq 6 say stop vehicle or check power supply?

Short answer: On the Ioniq 6, warnings about the 12-volt battery or power supply, followed by reduced power or a dead car, usually point to the ICCU (integrated charging control unit). It's the part that charges both the big battery from a charger and the small 12-volt battery that runs the car's computers. Hyundai recalled 2023–2025 Ioniq 6s for this: the dealer checks the ICCU, replaces it and its fuse if needed, and updates the software for free.

Symptom: A '12V battery' or 'check power supply' warning, a 'stop vehicle safely' message, loss of power while driving, or a car that's completely dead. AC charging may stop working too.

What to check first

1. If you see a stop-vehicle or power warning, pull over somewhere safe. The car can lose drive power as the 12-volt battery runs down.
2. Check your VIN for recall 24V868 (which replaced 24V204). If it's open, book it now.
3. Call Hyundai roadside assistance rather than driving to the dealer if warnings are on.
4. Ask the dealer to test the 12-volt battery too. Owners say dealers often replace it along with the ICCU.
5. Ask about a loaner or rental early. Owners reported long waits for parts.

Likely causes

1. Failed ICCU. The recall covers inspection, replacement and a software update.
2. Drained or damaged 12-volt battery. Often a side effect of the ICCU no longer charging it.
3. ICCU fuse. Replaced with the ICCU under the recall.

What it usually costs

Under recall 24V868 the repair is free. Owners' bigger complaint was time without the car: one owner on r/Ioniq6 said the fix took 48 days.

Is it safe to keep driving?

No. If warnings come on, stop when it's safe and get it towed. The car can lose drive power while you're driving. Verify with a mechanic or dealer.

DIY or shop?

Dealer. It's a high-voltage part and a recall repair.

Recalls, bulletins and complaints in plain words

• Recall 24V868 (2022–2024 Ioniq 5, 2023–2025 Ioniq 6, and some Genesis EVs): the ICCU may be damaged and stop charging the 12-volt battery, which can cause a loss of drive power. Dealers inspect and replace the ICCU and its fuse as needed and update the software. If your car is part of this recall, the dealer fixes it for free.
• Recall 24V204: the earlier ICCU recall, replaced by 24V868. Cars fixed under 24V204 need the newer remedy too.
• Recall 25V606 (2023–2025 Ioniq 6): the charging port door panel may come off. Dealers add adhesive for free.
• NHTSA complaints: 78 keyword-matched complaints for Hyundai Ioniq 6 2023–2025 (of 131 unique complaints queried, NHTSA complaints API by model year, queried 2026-10-21; keywords: ICCU, 12V, loss of power, power loss, charging, stop vehicle, shutdown, dead). This counts complaints that mention these words. It is not a defect finding.

What owners report

• In ICCU fixed after 48 days and a new 12V battery on r/Ioniq6, an owner said their ICCU repair took 48 days and the dealer also replaced the 12-volt battery.
• In And another iccu failure on r/Ioniq6, an owner reported another ICCU failure and owners compared how long their repairs took.
• In 2024 Ioniq 6 ICCU on r/Ioniq6, owners discussed ICCU problems on a 2024 car.

Quick tip

If you're buying a used Ioniq 6, ask the dealer to print the recall history. You want to see 24V868 completed.

Vehicle focus: 2023–2025 Hyundai Ioniq 6.

Safety / mechanic note

Loss of drive power can happen while driving. Verify with a mechanic.