What 381 owners told NHTSA about the 2023 Hyundai Ioniq 5 N

Iccu failure. Vehicle stops working completely

NHTSA ODI 11734182

These cars had an open campaign earlier in the year to check for faulty ICCUs. Mine was check in Jan and deemed to be good. In early Feb I was driving home alone late at night and suddenly I was unable to go faster than 20mph and in a matter of minutes the car shut off. It had to be towed and the dealer informed me the ICCU failed. It was very scary and extremely dangerous. This has been happening so often with the Ioniq 5's and there should be a mass recall.

NHTSA ODI 11651794

When using the one pedal driving or "iPedal" mode, the brake lights do not illuminate when braking unless your foot is completely off of the accelerator pedal. This is very dangerous because the vehicle can be stopped very hard without completely removing your foot from the gas pedal. I have stopped using this mode after almost being rear-ended three times within a week due to the car behind me not realizing that I am braking. This issue is gaining media attention. After doing research online, I have learned that there are lots of other people that have noticed the same behavior and have stopped using this mode as a result.

NHTSA ODI 11530475

When my car is configured to one pedal driving mode (iPedal), the brake lights only illuminate when the accelerator pedal is fully released. This means the car may decelerate rapidly (up to 0.25G or 2.5m/s^2 according to a report) under regenerative braking, while the brake lights remain off. I believe this is a safety hazard that can increase the chances of rear-end accidents.

NHTSA ODI 11523936

The Ioniq 5 when using level 2 regen, level 3 regen, and i-pedal (one pedal driving), does not turn on the break light when decelerating, even if coming to a full stop unless the driver removes their foot completely from the pedal or hits the break pedal. These driving modes allow the driver to perform regenerative breaking almost to a complete stop without turning on the break lights and warning other drivers behind you. With i-pedal specifically, the driver can 100% perform all stop and go traffic maneuvers without using the break and never have the break lights activate. This appears to be the default behavior of all Ioniq 5 vehicles and is controlled via software. The vehicle does not appear to measure rate of deceleration so even if the driver were to decelerate rapidly, the brakes would not activate. This has been extensively demonstrated on youtube and the best video example of this problem can be found here: https://www.youtube.com/watch?v=U0YW7x9U5TQ

NHTSA ODI 11524021

The Ioniq 5 offers a multi-level regenerative braking system, which slows the car down to varying degrees when letting off the accelerator pedal. While these systems work well to increase efficiency, the behaviour of the brake lights while in use is concerning. Very often the car is slowing considerably, enough to be akin to light braking, but the brake lights do not activate. This can be full let off the accelerator pedal and slowing with not brakes, or with a partial lift (especially on higher regen levels), where the vehicle is obviously slowing but the brake lights do not activate. This has been talked about on various forums and some review videos, and I expect this is not the first complaint placed about this issue. So far it has not caused a problem with my vehicle, but I have had to alter my driving habits to account for this, and it at times renders some of the vehicles technology dangerous to use, despite that technology being added to the car as a benefit to the driver under most conditions.

NHTSA ODI 11521709

When using i-Pedal (one-pedal driving) mode in this vehicle, it can decelerate at a very fast rate but does not illuminate the brake lights unless the driver’s foot is completely off the pedal. For example, I can be driving 60mph and decelerate to ~2mph as quickly as other drivers coming to a complete stop, but my brake lights will not illuminate until my foot is **completely** removed from the pedal. This is contradictory to the way one-pedal driving works, since coming to a smooth and slow stop requires that you slowly lift off the accelerator pedal, during which the brake lights do not illuminate because your foot is still pressing the pedal (albeit less and less as you come closer to the stop).

NHTSA ODI 11511276

While driving in the one pedal driving mode (“iPedal”), it is possible to rapidly slow the vehicle while keeping the accelerator pedal slightly depressed, which is the expected result for this regenerative braking mode. While rapidly decelerating in this mode, however, the brake lights do not illuminate while the accelerator pedal is slightly depressed. Even though regenerative braking is active and the car is rapidly decelerating, there is no brake light illumination. The brake lights only turn on if the accelerator pedal is not pressed at all, which during typical one-pedal driving only occurs at the very end when coming to a complete stop, or when stopping suddenly during a cut-in or at a light. This is a serious safety concern because the vehicle will decelerate very quickly with no visual warning lights to other drivers behind the vehicle. I have noticed that this issue has been reported by other drivers online, but I have not yet taken the vehicle to be inspected by the dealer. There is no indication of failure on the dashboard.

NHTSA ODI 11509945