Hyundai's and Kia’s Charging Unit Issues Cause Problems for EV Owners

The ICCU is a small box that sits at the rear of many recent Hyundai and Kia EVs. According to Hyundai Kefico, the automotive supplier that manufactures the part, the ICCU converts high voltage to low voltage. It’s involved with recharging the battery and powering important vehicle functions. Think of it kind of like the alternator on a gas-powered car: If it stops working, some electrical systems will shut down, and the vehicle will eventually stop running.

The specific ICCU in question is used by Hyundai, Genesis, and Kia. Hyundai owns Genesis and has a 33.88 percent ownership stake in Kia, and the three brands often share parts. 

“Sharing parts and designs across multiple models and brands can bring great efficiency and cost savings. However, that means a single fault can affect several models,” says Jake Fisher, senior director of Consumer Reports’ Auto Test Center.

Some owners of Hyundai, Kia, and Genesis EVs told Consumer Reports that their vehicles wouldn’t charge and that their vehicles lost power while driving. “I love the car, but when the ICCU fails and it comes to a dead stop on the road, it is hard to want to keep it,” said one owner. 

We heard similar stories from Corbin, who runs the Hyundai Ioniq-specific YouTube channel, The Ioniq Guy, as well as a Facebook group for Ioniq owners and enthusiasts. He also says that complaints have increased now that the weather is colder across much of the country.

According to Hyundai, the issues are related to a transistor, known as a MOSFET, that could blow a fuse in the ICCU and keep the vehicle from charging the 12-volt battery. A Kia spokesperson told Consumer Reports that the problem is due to “thermal loading and transient high voltage.” Even though these cars are electric, their 12V batteries serve a similar function to the starter batteries in gas-powered cars and are separate from the high-voltage battery that powers the vehicle.

Both automakers say that software updates and parts replacements should fix those issues, but Consumer Reports’ data shows that hasn’t always been the case, with owners reporting multiple replacements on the same vehicle. Repairs can often take several weeks due to parts availability, and one owner reported a wait of two months.

Corbin says that owners tell him the same. “Owners who received the software updates still experienced failures, and brand-new cars continue to fail,” he says. “Based on social media posts, some owners have already gone through three ICCUs in the few years the car has been on sale.”

Because a functioning ICCU isn’t required for DC fast charging, owners may still be able to charge at public chargers even if the on-board charger fails, but it’s only a temporary fix. “Eventually, the 12-volt battery will drain because it isn’t charging, and then the car will just power down while driving,” says Corbin. “Many reports indicate people suddenly losing power in intersections and on the highway.”

“If you already own one of these models, make sure you pay attention to all recall notices, and stay in close touch with your local dealership about repairs,” says Consumer Reports’ Fisher. “If you feel that your local dealership isn’t helpful, try another one nearby, or contact the automaker directly.”

If your car starts losing power, having charging issues, or showing error messages such as “charging error” or “check electric vehicle system,” contact your local dealership immediately. Otherwise, you might risk getting stranded without a charge. If your vehicle goes into “limp home” mode, where it can be driven only at low speeds, pull over and call for a tow truck.

Hyundai tells Consumer Reports that it is working with suppliers to get parts to dealerships as quickly as possible, and that the automaker will reimburse certain out-of-pocket expenses related to the recall. Kia says that parts distribution centers have replacement ICCUs and fuses in stock.