It could be when the transmission downshifts from 2 to 1. Does it happen when you are about to come to a complete stop?

 

Yes, it usually happens when decelerating and very rarely when accelerating. It happens when I'm about to stop or generally when I press on the brake to slow down.

 

Sounds like what I experienced, In my case, I have narrowed it to down to the 2 to 1 downshift. The issue sounds similar even though I have an 8-speed transmission and yours is a 6-speed. My original transmission had it and so does the replacement one:

Full stop issue

I have decided to do another post regarding an issue that happens when coming to a full stop. I have a 2018 2.0T and I have noticed this on two other brand new 2019 2.0T that I have driven recently. To put it simply, if I'm going at least 10 km/h (6 mph) and come to a full stop and then release...

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Check your idle RPM is not too high.

 

Harsh downshift is semi-common on the 6 speed. If it’s under warranty have your dealer submit it. If not, just live with it, it won’t cause any issues it’s just annoying

 

my 2015 SE has the same issue, when gradually slowing down, it feel like it bangs a bit when downshifting. If slowing down in neutral it is smooth, was how I diagnosed it.

It is annoying in that it did not do it for quite a while, then gradually started. Almost hard to notice at first.

 

I had something like that and then a week later my master cylinder got stuck
Burnt all the brake pads and destroyed the rotors.
But, not sure that is your issue.

 

Scan for pending or stored codes.
Change the ATF if over 30k miles. I would minimally check the ATF level and top off as needed.

If its too abrupt, could have a loose or broken motor/trans mount.

 

It doesn't happen all the time, maybe once or twice a week, on a per drive basis. I live in California so it isn't that cold to begun with but I did notice the jerking happens when it is cooler, at night or early morning.

The jerk isn't super hard and there is like a "thud" sound, I assume it probably is from the jerking. My car sorts of lunges a little forward kind of like if someone bumped you from behind. It feels like I slammed the brakes for a split-second when I was just gently pressing on it.

I have a 2016 Hyundai Sonata and checked it out at a Firestone. The mechanic said that the old owners installed the rotors wrong so they would have to change them and that would stop the jerking. I went to another mechanic to have the rotors changed and it still jerks afterwards. I'm thinking maybe it is a transmission issue? ABS? Fault Speed Sensor/Transmission control solenoid? Or maybe Fuel Injector? I'm not sure where to start to get this car checked out since the jerking doesn't always happen so the mechanics can't duplicate the issue. Thanks for any advice/help!

I have a2015 with the same problem

 

All Hyundai's have common problems, I have determined that!!! If there's a problem, it's common in a Hyundai lol

 

I don't have this on my auto 2015, but I've seen this on another car that was used for delivery. It was definitely a mechanical problem caused by intense use, the car was used with hard stopping and quick take offs. Can't point where the actual problem is, maybe transmission related, possibly the 2nd to 1st downshift is being delayed and finally comes with a kick.

 

Sounds like it could be a bad solenoid or valve body within the transmission.

 

Hi
Is that issue resolved?

 

I had this last year and then it went away. I started downshifting manually for engine braking, while driving down an incline street to a stop. After doing this for a while, I noticed that a few moments before the full stop, the transmission will give a 'kick'. I then stopped downshifting manually on that street - used only the brakes to slow down - and after a while that 'kick' disappeared completely, and never came back to this day.

I don't have a technical explanation for this - but it may have to do with some sort of wear on some transmission components. Maybe the transmission can compensate for some wear - to an extent - by adjusting the solenoid operation. I'm now at 40k miles on the original fluid, 2015 Sonata 6 speed auto

 

So that happened to me and I replaced the transmission and clutch oil and the problem went away and I heard that with the other owners, did you ever get your transmission oil and clutch oil replaced at any point?