I bought the car used (the prior owner passed away) It only has 44,000 miles on it. When the cold weather started, the jerking began. At 20 mph when decelerating, the car jerks as if someone is hitting me from behind. When making right hand turns I am afraid that I will lurch into oncoming traffic. I contacted Hyundai corporate and told them of the issue and asked them to cover it under warranty. They refused and refused to acknowledge that there is even an issue or TSB regarding the issue.

The dealership ran the ECM TSB 10-AT-007-1 update but it did not help. I have submitted a complaint with NHTSA. I cannot in good conscience sell the car. I do not want to pay for a new transmission when Hyundai knows that they are selling a faulty product and arbitrarily decided not to honor the warranty beyond the first owner (who died). Please help.

Noticed this about 1-2 years ago (2016/2015). When the temps are below 30 degrees, my Sonata will lurch/shift roughly as you go to slow down around the 20 mph on the speedometer (possibly 2nd or 3rd gear) within the first 15 minutes of driving it. Even if it is sitting outside running to warm up for 15 minutes before driving it, it will still do this.Once the car has been driven and warmed up fully, it will go away. I have dropped it off numerous times at a couple of mechanics to get looked at and every time, the car would not perform the rough downshifting for them like it does for me. Still intend to try and have this addressed.

Have had the 09 Sonata for just over a year, bought it pre-owned with approx 35k miles on it. A couple hundred miles ago it started having a rough times shifting. It's an automatic, I've been driving this car for a year, i know how it normally acts. When accelerating it will get into the 'red-zone' before it shifts up. And this is at normal level of usage. It's not being accelerated in a manor that would necessitate this. It does this for each time it shifts until you're into fifth gear, and then it hesitates when slowing down, the RPMS will drop below 500 before it'll down shift. I have recently had to use the shiftronic override to get it to shift as it should.

Thankfully it's under warranty, but this is really very rough and unsafe to drive. It's at the local dealership, however I feel as if I'm going to be dicked around. Being how they have a D rating with the BBB and the guy said he's never heard something like this. Thankfully I can take the diagnostics test to another dealership if it's not fixed. I'm really worried that this investment may not have been a wise-one, and am strongly considering not purchasing another Hyundai even though I would consider myself a loyal Hyundai owner, since my first and 2nd vehicles have both been Hyundai's.