Driving down 95 in Virginia, the car started to no longer accelerate and make alarm sounds inside the car, and the dash board lit up like a Christmas tree. Pulled over to the shoulder and turned the car off. I let it sit for a while and restarted, was able to drive about 5 more miles before it did it again. Was able to drive like this for about 30 more minutes before it wouldn't drive no more. I got it towed to the dealer, ended up getting the hybrid battery replaced. Something I was informed when I purchased the car never happens. I was excited to know it was still covered under the warranty as the battery cost more than the car itself.

I purchased, new, a 2011 Sonata Hybrid from Southern States Automotive on or about 4/4/2012. Currently the odometer shows 62,500. I like the car except...

Initially, the Hybrid performed satisfactorily...the EV mode responded to hybrid battery level and driving conditions easily delivering 40-45 mpg highway. About three years into ownership, the EV mode began losing response and did not function as often as road conditions would allow. I observed this condition continue to deteriorate for another year.

In October, 2016, I contacted Hyundai National Customer Service which suggested I take the car to the dealer for evaluation of the hybrid system. On or about November 3, 2016, the dealer's response was “everything is fine” but did not address the core issue because they said the 12v battery was okay.

In January 2017, Hyundai National Customer Service was contacted to obtain an case number. Again, I was told to take the car to the dealer. On or about March 30, 2017, the hybrid was taken to another dealer, Johnson Hyundai. Again, the problem was not diagnosed properly even though Techline was involved...the EV system did not perform properly.

After four trips, two dealers, and two Regional Customer Service agents (Nicole Parker and Christina Short), the Hybrid was finally reprogrammed with the correct software versions by Ray Trombley, Southern States Automotive or or about August 15, 2017. For a while, the EV mode appeared to function properly. However, after a recall to replace a defective steering coupler on or about December, 5, 2017, the EV mode once again did not perform based on road conditions.

I captured on several videos the EV mode, hybrid battery level and road conditions. The videos show lack of EV performance. I shared one video with Jamie Holcomb, Service Manager, Southern States Automotive and with Christina Short, Regional Agent. The video demonstrated more than what a mere OBD scan would demonstrate. Rather than take the hybrid to the dealer, I suggested the video be used by a skilled technician to diagnose the problem but to date no one has responded with a path to a solution other than “take the car to the dealer”. I have contacted Brian McInerney, General Manager, Southern States Hyundai , (919) 839-7300 but no response. Folks have been courteous, however, no one has taken ownership of the problem. I have had to shepherd this issue myself.

After a letter to Omar Rivera, Hyundai Director of Quality and Service Engineering, things moved forward so I thought. Christina Short was very helpful and shortly a Field Service Engineer was scheduled to evaluate the situation. After the evaluation, the response was that everything checked out. I shared a video of the hybrid system performance on a flat road in Florida which demonstrated the hybrid battery remained fully charged for miles without EV mode energized. The official response was no explanation for the observed and everything is okay. I have several videos showing the same problem over miles and miles.

I asked for a copy of the Field Service Engineer's report but was refused on the grounds it was proprietary. I do not accept this reason. I believe I deserve a detailed explanation for why the current hybrid performance is considered okay when it doesn't function as advertised.

The last word from Hyundai is my case is closed and not further work will be done. I believe more attention to this problem is deserved.

The problem may be a challenge to solve or costly to repair under warranty, but the problem is real as consistently shown on the videos. It can be solved by an engineer intimately familiar with the EV system. The symptoms point to a potential Inverter/Converter and associated circuitry issue.