Why did my 2022–2024 Hyundai Ioniq 5 say 'Check EV system' and start losing power?

Short answer: On the Ioniq 5, a sudden 'Check electric vehicle system' warning, a 12V battery warning, and power that keeps dropping is very often a failed ICCU (Integrated Charging Control Unit, the box that keeps the small 12-volt battery charged from the big drive battery). When it fails, the 12V battery slowly drains and the car goes into a reduced-power mode. Hyundai's recall replaces the ICCU and its fuse when needed and updates the software for free.

Symptom: A 'Check electric vehicle system' or 12V battery warning, the car limiting speed (owners report 30 mph or less), flickering screens, or a 12V battery that keeps going flat.

What to check first

1. Run your VIN for recalls 24V204 and 24V868 at hyundaiusa.com or nhtsa.gov/recalls. 24V868 replaced the earlier recall, so cars fixed under 24V204 still need the newer repair.
2. If the warning comes on while driving, pull over somewhere safe and call Hyundai roadside to tow it to a dealer.
3. Check the 12V battery voltage with a cheap multimeter. One owner confirmed the ICCU fault because the 12V voltage was low and didn't rise when the car was switched on.
4. If a jump start brings it back and it then drives and charges normally, the 12V battery itself may be the weak link. Have both checked.
5. Ask about a loaner up front. Owners report waits of weeks for ICCU parts.

Likely causes

1. Failed ICCU (Integrated Charging Control Unit) or its fuse. Hyundai's recall says the ICCU can be damaged by electrical overload and stop charging the 12V battery. Dealers inspect it, replace the ICCU and fuse if needed, and update the software.
2. Weak or damaged 12V battery. A 12V battery that has been drained flat can stop holding a charge. Owners in r/Ioniq5 say a battery that 'tests fine' can still be bad.

What it usually costs

The ICCU repair is free under the recall. For the 12V battery, one r/Ioniq5 commenter suggested a store-brand AGM battery for about $180 and said they had heard of Hyundai reimbursing owners after a battery failure. Ask Hyundai before you pay.

Is it safe to keep driving?

No, not once the warning is on. Hyundai's recall says the car keeps driving in a fail-safe mode with less and less power, and could eventually lose drive power completely. Get off the road safely and have it towed. Verify with a mechanic.

DIY or shop?

Dealer. The ICCU is a high-voltage part and the fix is a free recall. Checking or charging the 12V battery is DIY.

Recalls, bulletins and complaints in plain words

• Recall 24V204 (March 2024; 2022–2024 Ioniq 5, plus Ioniq 6 and some Genesis EVs): the ICCU can be damaged and stop charging the 12-volt battery, which can lead to a loss of drive power. It was later replaced by 24V868.
• Recall 24V868 (November 2024): the updated recall for the same problem. Dealers inspect and replace the ICCU and its fuse as needed and update the ICCU software. If your car is part of this recall, the dealer fixes it for free, even if it was already repaired under 24V204.
• NHTSA complaints: 654 keyword-matched complaints for Hyundai IONIQ 5 2022–2024 (of 1,019 unique complaints queried, NHTSA complaints API by model year, queried 2026-10-17; keywords: iccu, 12v, 12 v, 12-volt, 12 volt, integrated charging).

What owners report

• In Failed ICCU – My Experience, a 2023 SEL owner with about 7,500 miles got 'Check electric vehicle system' with no warning, was stuck at about 30 mph, and confirmed the 12V voltage wasn't rising. They kept a battery charger on it until the dealer appointment. The car had every earlier software update and the ICCU still failed. The biggest complaint was the month-long wait for the part.
• Another owner asked Do I have ICCU failure? after warnings and a car that would barely move.
• In 12V dead? Or ICCU?, a reply explained that if a jump start gets the car going and it doesn't shut down or throw warnings while driving, a damaged 12V battery is more likely than the ICCU.
• An owner in 5 Months to Replace ICCU described a very long wait for the repair.

My take

My advice as a former finance manager: if you're buying a used Ioniq 5, ask the dealer for a printout showing 24V868 was completed. If it wasn't, get it booked before you sign, and ask in writing who covers a loaner if the ICCU fails while you wait.

Vehicle focus: 2022–2024 Hyundai Ioniq 5.

Safety / mechanic note

A car that keeps losing power can stall in traffic. Verify with a mechanic.