2024 Hyundai Ioniq 5 Powertrain & Transmission Problems

ICCU failure. Common problem but Hyundai seems to have no fix despite it happening for years now.

While driving I received the infamous "Stop vehicle and check power supply" warning, and it was then inoperable, needed a tow to the dealer for ICCU replacement. I can't believe you terminated your initial investigation into this in 2023 because they did a recall (which my car received). That recall did not fix the issue. It is March 2026 and Ioniq 5 and other models with the same electric system are dying on the road at the same rate as before. There is a large percentage of failed cars, and every failure is dangerous. This is a huge safety issue, and is not receiving adequate oversight by the NHTSA.

I was merging onto the highway. I got a warning that I needed to check my electrical system. I was able to back down the highway ramp and park on a side street. Within 20 minutes the car was fully dead and AAA needed to tow it to the dealer. The dealer confirmed that the ICCU needs a replacement. My family is lucky this happened in a place we could safely get to a side street. Had it happened 5 minutes later we would have been stranded on the highway with 2 small children.

According to Hyundai, all active recall campaigns have been addressed on this vehicle (NHTSA site says it wasn't, Hyundai claims it was on 9/22/2025). Last night (3/3/2026) while driving on an unlit, two-lane country road about 20 minutes from my house, I heard and felt a bang noise from underneath the rear cabin of the car accompanied by a message stating "Stop vehicle and check power supply" on the dash. The car immediately went into a limp mode, reducing speed to ~40mph. After about 0.5 miles, the car further reduced speed to about 25mph (in a 55mph zone). As speed reduced further (no indication of what the speed would be reduced to), I pulled the car off of the road and awaited tow service. As this happened in the evening on an unlit country road, I was forced to wait for assistance along a stretch of road that could have been hazardous. Hyundai's claimed recall campaign work was performed on 9/22/25 with subsequent recurring failure about 5 months later. The dealer cannot confirm the diagnosis or offer estimates of repair time/availability until they see the car (currently scheduled for next week).

Vehicle displayed "Power limited" and slowed to a crawl, was able to drive less than a quarter mile to a safe place before it displayed "Stop vehicle and check power supply" then completely shut down. Diagnosed as ICCU failure by the Hyundai Dealer service technician, with the parts on backorder and no ETA for the 15 or so other Hyundai Ioniq 5's with the same failed ICCU waiting at the same dealership, in front of me.

“Check electrical system” warning while driving. Sudden loss of power and speed. “Turtle mode” icon. Limped home 2 miles at <10mph. Vehicle bricked. Towed to dealership.

ICCU failure: confirmed by dealership, submitting for your records - while driving the morning of 2/11/26 in Evansville, IN a warning message appeared on the dashboard stating 'Check Electric Vehicle System' followed by a rapid deceleration. Luckily there was not a vehicle behind me as they would have rear ended me. This failure occurred without warning and presented a significant safety hazard, leaving the vehicle stranded in traffic until I was able to restart it. Vehicle went in to turtle mode upon restart, would not go over 20mph at first then I stopped the car, restarted it again, it would move for 15-20 seconds before going in to turtle mode again and now it will not go over 10mph - interestingly, when I would stop and put it in reverse, the vehicle would move 10-20' and then come to a very abrupt stop as the entire vehicle shut off - had to tow the vehicle to the Hyundai dealership in Evansville Indiana where the ICCU was confirmed has having failed

The car stalled while being driven by my son. It displaced an error code. The Car had to be towed to dealership. It was diagnosed with ICCU unit failure. Needs to wait over a months for parts.

Received multiple "Check Vehicle Electric Systems" on a drive which went away and then got into the car, turned it on, shifted into drive, and heard a pop from bellow before moving at all and the car went into Turtle Mode and blasted warnings. The car completely died with zero power leaving it stranded in sub freezing temperatures and unable to lock the car or open the lift gate to access the trunk area. Eventually it was towed to the dealership and was diagnosed to have a faulty ICCU which took 5 weeks to replace.

On the morning of [XXX] I received an error message on my dashboard (attached) "Stop Vehicle and Check Power Supply". The car had started to lose acceleration power to no more than 30MPH. I contact the service department at my local dealer. They instructed me to bring it in or have it towed. I was about 2 miles from home so I headed back. While in transit the car lost all power in the middle of traffic. It stopped completely ! No emergency flashers, lights, power for the doors, windows, etc. I could not even put into Park. If I lifted my foot off of brake, it started to roll backwards. Luckily I was not on the expressway or at a railroad crossing. Fortunately a local police officer saw my dilemma and directed traffic and pushed my car to the side of the road ([XXX]) After doing research online I found this to be a common issue with Hyundai/Kia EV vehicles. The ICCU fails with no warning leaving drivers stranded.. The unit is on backorder because of so many failures and there is no ETA INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

12 volt battery drained in my driveway on 1/20. Vehicle was completely dead including door and hatch locks. Roadside assistance jumped the 12 volt battery. Vehicle message said, “Insufficient power. Check Electrical system”. Vehicle was towed to local Hyundai dealer, who diagnosed an ICCU failure. The dealer has four other Ioniq 5s with the same problem. Replacement ICCU is on back order with no ETA for delivery. There were no warnings prior to the ICCU failure. If the vehicle were being driven when this failure occurred, the loss of power would have put all occupants at great risk.

On January 1st 2026 around 11am we were traveling in rural Wisconsin when we heard a loud pop from under the back seat . This we now know from Dahl Hyundai in LaCrosse was the ICCU failing . When this happened we were in blizzard conditions and the car forced us into limp mode and reduced us from 55 mph down to 25mph in bumper to bumper traffic on a rural hwy (this was not a smooth speed transition the car performed ) We drove the vehicle back to the nearest town going 25mph as it was alerting us that we were on limited battery as this issue in short time will make the vehicle inoperable . We found a safe place to stop and did so. We called Hyundai Roadside assistance who then let us know it would be 9 minutes until we received help. This would actually take 4 more hours . They left us with a car that did not operate , produce heat in a blizzard . We eventually had family pick us up so we were safe . We still do not have the vehicle back as Hyundai America has the part (ICCU) on back order with no ETA of repair. .

Warning light came on stating that we needed to have the electrical system checked asap. Vehicle would not charge from Level 2 charger. It needed to be towed from our house to the dealer to get its ICCU replaced since there was a risk that it would no longer power vehicle on 4 mile drive to dealer for repair. Problem was fixed in one week by Roseville Hyundai by replacing the ICCU in the vehicle

While driving, I heard a loud pop in the rear passenger side and subsequently, the dashboard showed an error to "stop vehicle and check power supply". After driving about 15 minutes, another error showed on the dashboard "12V battery voltage low. Stop safely". After coming to a stop, the vehicle completely shut off and would not turn back on. A tow truck was called and my vehicle was towed to a Hyundai dealership. The vehicle is now at the service center at a Hyundai dealership. The dealership confirmed it was an ICCU failure. While there was not a crash or any injury, the known defect from Hyundai left my wife, my [XXX] daughter, and me, stranded 60 miles away from home, in the middle of the night. Luckily we were pulled over safely and not in the middle of the highway. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

The ICCU failed while driving. A loud pop occured 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. This car was part of a recall last year to prevent this issue, however only a software fix was performed. Luckly I was able to get the car home on a very cold day.

My 2024 ioniq 5 has no recall but they have a well known issue where the ICCU does not charge the 12v as expected. this results in loss of power. In my situation, i was driving on the freeway at 65MPH when i got the low 12V battery message and my car slowed down and I was not able to accelerate at even street speed. I was fortunate enough to pull the car over from the left lane to the right shoulder as the traffic was light. This could have easily resulted in an accident. [XXX] INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

While accelerating onto a road with cars approaching from behind, vehicle entered limp mode and was restricted to 25 MPH. I was forced to leave the roadway to avoid a collision with the vehicle behind. The street this occurred on has a speed limit of 40 MPH. The vehicle's normal acceleration was sufficient to ensure a safe gap to the approaching car, but the time it took to recognize and react to the unexpected behavior reduced this gap. The dealer diagnosed this as an ICCU failure related to safety recall 272. All prior recalls were complete at the time of the incident.

The vehicle is less than 1 years old. Had 91% charge left. Turned in the car as usual. Turned in heated seats and heated steering wheel as the outside temp was 34 degrees. A pop noise occurred and my entire dashboard flashed like a Christmas tree saying electrical system failure. Pull over safety. The cars speed was reduced to 20 mph. This was extremely scary as this happened on a main road where the speed limit was 55. The ICCU failed according to the dealer. This has been a common issue among Ioniq5 cars and the manufacturer has failed to fixed this issue. This car presents a high failure rate of the ICCU computer that controls the entire car. Once this chip fails, the car can not be driven and it must be towed back to the dealership. This is not a one off. Hyundai also quietly remove the remote start feature to activate the heated seats. They must know that turning on the heated seats might trigger an overload causing possible risk of iccu failure.

The ICCU failed at 11,000 miles and 11 months into the lease. When the ICCU fails, the car becomes inoperable. This was a major safety hazard since it broke down on a major US highway and I was barely able to get off to the side of the road. This seems to be affecting a large number of Ioniq 5 and Ioniq 6 models.

When I started driving my car a warning to check the electrical system came on the display and the speed of the car dropped to less than 25 mph. The road we were driving on was over 45mph without a safe shoulder. After it was towed to the dealer, they diagnosed that the ICCU had failed and replaced it and a fuse. This was after all recalls and other software updates were performed many months ago.