— Hyundai is recalling 2,800 model year 2016-2018 Hyundai Sonata Plug-In Hybrid cars that can lose power while in electric vehicle (EV) mode.
These cars are equipped with voltage protection devices (VPDs) used to protect the high-voltage battery modules that may activate inadvertently.
In May 2017, Hyundai received a field report indicating a 2016 Hyundai Sonata Plug-In Hybrid couldn't start and the driver noticed an illuminated hybrid system warning light.
This was followed by numerous dealers making technical assistance calls to Hyundai reporting additional incidents, with one where the vehicle lost power while driving.
The problems caused Hyundai to open an investigation where engineers discovered if the VPD activates while driving in EV mode and the electric motor fails, the hybrid powertrain would default to the gasoline engine as a fail-safe.
Hyundai then issued a technical service bulletin (TSB) informing dealers about the problems, but Hyundai learned in certain conditions while driving in EV mode the vehicles could still lose power. The automaker discovered the vehicle might not default to the gasoline engine for power due to differences in the plug-in hybrid powertrain and the conventional hybrid powertrain.
The automaker finally replicated a mistaken activation of the VPD switch by an overcharged battery resulting in a stall while driving in EV model.
Hyundai is unaware of any crashes or injuries caused by the vehicles losing power, but the identical problems caused Kia to recall Optima Hybrid cars about a week ago.
The Sonata Plug-In Hybrid recall should begin May 4, 2018, when dealerships will remove the VPD switches and install new battery management systems that have overvoltage protection devices.
Owners may contact Hyundai customer service at 855-371-9460 and refer to recall number 175.