2017 Hyundai Sonata Plug-In Hybrid: sudden loss of power

Filed Mar 18, 2026 · Engine, Transmission · CA

To the federal safety agency, I am filing this formal safety complaint regarding a dangerous engine failure incident involving my 2017 Hyundai Sonata Plug-in Hybrid. Description of Incident: While traveling on CA-85 near Mountain View, California, at approximately 65 miles per hour, the engine suddenly and without warning lost all power. The vehicle began to slow down involuntarily in active highway traffic, creating an immediate and serious risk of rear-end collision. The driver had no ability to maintain safe highway speed or accelerate out of danger. The vehicle had to be towed from the scene to the dealership. There was no warning light or prior indication that engine failure was imminent. The failure was sudden, complete, and occurred at highway speed in heavy traffic conditions. Safety Risk to the Public: This incident represents a significant and ongoing public safety hazard. A sudden, unpredictable loss of engine power at highway speed — with no prior warning — places the driver, passengers, and surrounding vehicles at serious risk of collision. This is not an isolated mechanical inconvenience; it is a life-threatening failure mode. Known and Documented Defects: The 2017 Hyundai Sonata Plug-in Hybrid has been the subject of multiple recalls and class action litigation related to engine defects. My incident is consistent with the known failure patterns documented in those proceedings. Despite this history, Hyundai Motor America has denied my warranty claim, citing missed services — a characterization I dispute, as the vehicle was serviced exclusively at an authorized Hyundai dealership whenever the onboard system indicated service was due, and no technician ever identified or disclosed any engine damage during those visits. Request to the federal safety agency: I respectfully request that the federal safety agency: 1. Open or expand an investigation into engine failure incidents in the 2018 Hyundai Sonata Plug-in Hybrid 2. Investigate whether a recall is warranted

Filed Jan 23, 2024 · Electrical, Engine · CA

Vehicle lost power in freeway. Complete power failure. Early crashed into. Vehicle coasted to off ramp and towed away.

Filed Jan 4, 2024 · TX

About 3 weeks ago I had just left my house, battery fully charged and gas tank full. I was coming down a hill to a stop sign and started braking. Suddenly the car seemed to lose power and essentially stopped moving. There was an error on the dash saying "hybrid system failure". There was barely able enough power to slowly pull the car over to the side of the road. I turned off the car and checked the battery in the trunk - I didn't see any obvious concerns. My husband got there 10 minutes later and we tried turning the car on again. It came on fine but there was an engine warning light. We were able to drive it without difficulty back to my house. I was unable to get a timely appointment at my local Hyundai dealer, so a couple days later My husband drove it to a local garage to see if they could figure out what the problem was. When he turned the car on again the engine light was no longer on. However, at the garage they were able to pull up a history of the car alerts and it confirmed that it said hybrid system failure. I have done some research online and it sounds like there was a recall on Hyundai sonatas hybrids for 2017 but I did not see a recall for the plug-in version of the hybrid. I searched online, however, and there were many other owners of Hyundai sonata plug-in hybrids that reported the same incident. I am hoping that a recall gets is issued for the plug-in hybrid as well so that more owners don't have the same problem. If I had been driving on the highway at 65 mph in a middle lane and my engine suddenly lost power it could have been fatal. Oh - one other recent problem I had that I'm not sure is related is that my car recently started losing electric miles very quickly. From the time it was purchased until a few months ago, it was losing plug-in miles at about 1 mi per year (i.e. each year a fully charged battery gave me 1 mile less). Then about 6 months ago it started losing electric miles very quickly - about 1/mo. Dealer said it was normal aging.

Filed Sep 25, 2021 · Engine, Fuel system · CT

On August 31st 2021, While driving my 2017 Hyundai Sonata PHEV on interstate 95 the check engine and hybrid system warning lights came on and the car simultaneously lost power for 3-4 seconds, which caused a decrease in speed from 65 to approximately 50 mph. There was a tractor trailer behind me but thankfully it braked to avoid striking my car. The car regained partial power and I was able to drive it home. I took the car to the dealership to have it repaired. The dealer diagnosed a faulty battery management system, and replaced this component after 17 days. On September 25, while driving on a street the car once again lost power for 3-4 seconds, with the check engine and hybrid system lights simultaneously illuminated. There was a recall on my vehicle several years ago to prevent this dangerous problem. I had the car repaired at that time but clearly the problem was not fixed as my car has subsequently lost power on two separate occasions, in a manner that could have easily caused a crash.

Filed Mar 28, 2018 · Engine · 353 miles · DE

This is my first time buying a brand new car in my mid 40's. I purchased the car (plug in hybrid) with only 25 miles on march 15, 2018 and after 7 days and 353 miles later, upon driving and coming to a stop in the city of philadelphia, pa, the car stalled and lost power. Warning message "check hybrid system." I had to step on the gas pedal all the way down to the floor and waited a second or two in order for it to move at a turtle's pace. Fortunately, I was able to find a safe spot to park the car. It was towed to a local hyundai dealership near me and as of yesterday, 3/27, no diagnostic findings. I have notified hyundai motor america and they have opened a case#. I have also reached out to the selling dealer to help me with this matter. This is extremely upsetting and disappointing, especially for me as new car buyer!!!

Filed Mar 17, 2018 · Brakes, Driver assistance · 12,470 miles · CA

14 march 2018 10:30 am, 70 MPH on us 101 to san francisco, hev mode, rainy weather, 4 passengers for a business meeting. Car steering shuddered as if the tires slipped and spun on the wet pavement. Esc, brake, and auto hold lights turned yellow. Was able to drive the car normally to reach destination, parked, attended meeting, and started driving back home with my passengers at 3pm. Esc, brake, and auto hold lights were still on. Hev mode. 30 minutes later, I-280 at 65+ MPH, engine power drastically reduced abruptly, car started to slow down and became unresponsive to the gas. Turned on emergency flashers and with great difficulty in the evening rush hour commute traffic, managed to shift right three lanes and take the next exit, went into a parking lot and stopped the car. Consulted manual for any meaningful actions. Started car back up. Mil light also came on along with message to take car to dealer. Ran vehicle diagnostics and got 'a possible condition with the ecs has been detected and a full system check is recommended soon'. Started driving car again. Same lack of engine power. Drove through local roads and countless many traffic lights and reached home after 4 hours (normal = 1 1/2 hours). At home, plugged car in for charging. Charging started normally. Around 10pm, wanted to take a picture of all the lights, so pulled charging cable out and started car. All lights were off except mil! Decided to test drive and found no loss of power. Took it to nearby freeway, floored gas pedal. Car responded with full power! Next day morning, driving car to dealer, hev light and continuous warning beep came on, just a mile away from home.