In documents filed with the US National Highway Traffic Safety Administration, Hyundai explains that an internal leak in the Electric Power Control Unit (EPCU) could result in a loss of power or even a stall. Thankfully, Hyundai isn't aware of any injuries due to the malfunction despite multiple field reports of the power loss.
The automaker says that 853 Kona EVs from the 2021 model year are equipped with an EPCU that might have insufficient sealing at the DC-DC converter housing. Evidently, that error was caused by inadequate steam cleaning during production.
Vehicles that experience the potential internal coolant leak could end up with contamination of the main controller. In turn, that could trigger the Kona EV's limited mobility "fail safe" mode. It could also cause a sudden loss of power or even a total stall. Depending on the results of contamination, some owners could get warning messages on their driver information display.
Hyundai says that it'll inspect and replace the EPCU at no cost to the customer regardless of whether or not they're still inside of their warranty period.
Source: Carscoops