During labor day weekend, I was alerted on display that the "transmission temperature is high". I stopped for 40 minutes in a turnout area (the manual states that you need to wait 20 minutes in this case). I continued the trip, but the transmission was not shifting gear. I pushed the accelerometer and rpms were at 5000 and gear was not shifted (the speed was around 10-20 M/H). After a few attempts to increase rpms the gear shifted. The "check engine" light came on. I parked the car for 5-6 hours. On my way back the issue appeared after 20-30 minutes of driving. In my garage, I noticed that I'm not able to drive in the reverse direction. The reverse gear was not shifting. I felt like the vehicle was in neutral position. I was not able to park the vehicle. I had to push the car into the parking spot. The next day the light "check engine" turned off and the vehicle was shifting ok. I was able to drive the car to a Hyundai dealer. The service man was unable to verify the transmission issue. The diagnostic code was P191464. The service man contacted Hyundai fse. Fse advised replacing the shift motor actuator. The shift motor actuator was replaced. I picked the car up from the service today on September 25th. I drove from service to home without any issue ( approximately 6 miles).

- San Jose, CA, USA

When in drive, at low speeds (between 5mph and 10mph) the vehicle becomes jerky when decelerating, vehicle shudders as if troubling to change gears.

- Waretown, NJ, USA

Bought 2 brand new Sonata with top technology package on 4/15/2015. The problem happened on both new cars. Whenever the gas pedal is off, the computer/software take control of slowing the car down even with open road ahead, on flat surface, on corners, up or down hill. This happened whether it is in eco, nor or pwr driving mode. At various stages, the brake kicks in at various speed and the transmission downshift prematurely; in deceleration, the RPM will only goes down until idling speed, but I can see the RPM goes up a few hundred RPM at least twice before the Sonata come to a complete stop" Sonata does not have "hill decent control" like the range rover for specific safety reasons. In cruise control, it is even worst. If you set cruise at 60, later speed up to 80 to pass a slower car, once you let off the gas pedal, the car hit the brake and slow you back to 60? what is the hurry? coasting is drivers best friend because it means free mileage. Yet Sonata engineer thinks otherwise. This erratic behavior would certainly irritate the driver behind you enough and even cause road rage. If the Sonata decided to hit the brake by itself at a fast corner, what will happened? there is an article in detroit bureau mark B, said his 2012 equus spin out of control and no one understand why" I brought back the car twice to the dealer and both the mechanic and the sale manager defend their product. Attach article from detroit bureau. www.thedetroitbureau.com/2014/06/Hyundai-counts-on-Alabama-plant/comment-page-1/#comment-180948.

- Campbell, CA, USA

On 04/06/2016, the vehicle's engine began to run rough and hesitated. Lack of acceleration, even at 4000 rpms (top speed 20 mph at 4000 rpms). The vehicle began to stall and required the gas pedal to be pressed due to low rpms at idle. The problem is intermittent, with no warning to the operator, and poses a significant safety risk on roadways with speed limits above 40 mph. No engine warning light came on to warn the operator. After three occurrences of this problem, in less than 24 hours, the vehicle, with only 1,351 miles on the odometer, was taken to dealership for service on 4/7/2015. After replacing, the fuel pump, the vehicle was returned to the owner on 04/10/2015. Less than 2 miles after picking the vehicle up from service, the problem occurred again, on a 50 mph roadway. The operator was very concerned for her safety as other motorists were swerving around the vehicle and honking their horns. Again, no engine warning lights came on to warn the operator. Once again, the vehicle was taken back to the dealership within 20 minutes of initial pick-up, for further repairs. The dealership has had the vehicle ever since, changing multiple parts dealing wit the fuel systems, and has yet to correct the problem to date (04/16/2015).

- Bel Air, MD, USA

I went to accelerate, by depressing the accelerator, and the engine revved high, but, the car did not accelerate and there didn't appear to be power at the wheels. It acted as if the transmission was slipping. I let off of the pedal and it downshifted and power to the wheels was restored. I repeated this process 3 times after and I could replicate it every time. Drove to the dealership and left it for service. They drove it the next day and couldn't replicate the issue. I have not been able to replicate the issue since that day either.

- Dublin, OH, USA