Poor Shift Quailty of Automatic Transmission on Hyundai Sonata

Prior to replacing the automatic transmission fluid (to improve shift quality), make sure that the transmission fluid level is correct. Also, make sure the computer that controls the transmission has the most up-to-date adaptive programming information. When servicing these transmissions be sure to use fluid approved by Hyundai.

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Average mileage: 65,640 (10,000–151,000)
Drive Train affected: Automatic Transmission
8 model years affected: 2005, 2006, 2007, 2008, more2009, 2010, 2011, 2012
74 people reported this problem
54 people shared problem details
2010 Hyundai Sonata- Automatic Transmission65,000
I noticed that my car is beginning to down shift with a hard thump at 20mph. Has anyone had this problem? Kt
Upvoted (31)Flag Inappropriate
Sonata Limited.I've had transmission problems starting at about 6 mos. and several times since...ECM & hard shifts, like someone hit me! The ECM should be covered by warranty. Poor gas mileage since about same time but ironically, this specific yr/model excluded from the class-action lawsuit that was awarded. Too many other problems to list. I'm afraid to take on trips, too. What a lemon! I'd never buy another one! Shame cuz a beautiful car...but looks don't make it run and get me where I need to go. Going back to Toyota!
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2009 Hyundai Sonata- Automatic Transmission80,000
Last year my Sonata started downshifting when driving on the freeway, on its own. I paid over $100 to get the dealer to fix it. They said it was a software glitch and they fixed it by loading new software. That was 2013. Now (2014) it downshifts hard when I'm braking in city traffic. If I'm going to have to pay this every year, I may be done with Hyundai. Other than this problem, it's been a great car. Hyundai needs to take ownership for this defect.
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2009 Hyundai Sonata- Automatic Transmission71,000
Hard violent downshifts when drive car while cold. Almost disappears after warmed up. Harder upshift when cold. Will be taking to a dealer to diagnos issue.
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2010 Hyundai Sonata- Automatic Transmission
HARD down-shift always between 20 - 25 mph.
At times,before reaching normal operating temp.transmission would shift into next gear with a very very hard jerk.This would not happen all the time.Thank you
2009 Hyundai Sonata- Automatic Transmission60,000
In cool weather the transmission downshifts with a hard lurch at 20 mph, after warming up it seems to go away.
2009 Hyundai Sonata- Automatic Transmission60,000
Hard downshift from second to first when cold.
2009 Hyundai Sonata- Automatic Transmission96,000
not fixed, I shift into neutral, when coming up to stop signs--Jerky downshift -- if I don't put it in neutral.
2009 Hyundai Sonata- Automatic Transmission65,000
Each morning when coming to a stop harsh down shift into 1st gear, but will go away after warmed up. Took into dealership and they did update to ECM, which was not covered under warranty, so much for the 10yr 100,000 mi warranty.
2011 Hyundai Sonata89,000
Shift problem
2011 Hyundai Sonata50,250
It shifts hard when I put it in reverse, the whole car shakes. I haven't fixed it yet, just looking into it.
2009 Hyundai Sonata- Automatic Transmission98,500
At low speeds I get a very rough unexpected down shift. I'm going to have the transmission fluid changed and have the check the software when serviced.
2009 Hyundai Sonata- Automatic Transmission50,000
My 4 cylinder 2009 Sonata shifts hard from 2nd down to first until the transmission warms-up. Sonatas should be recalled for software upgrade. I may wait until the tranny goes then have manufacturer replace under warranty.
2006 Hyundai Sonata105,000
middle gears noisy, difficulty shifting; still accelerates, but sounds like it's still in 3rd gear - even on the highway!
2010 Hyundai Sonata- Automatic Transmission75,000
My car isn't shifting when trying to pick up speed. My paddle shifters work or it would be not be drivable.
2009 Hyundai Sonata- Automatic Transmission114,000
Pauses when downshifting from third to second. Dealership said there are no campaigns for this model. Had the transmission flushed and now the problem is worse.
2007 Hyundai Sonata150,500
Shit from drive to drive one
2009 Hyundai Sonata- Automatic Transmission70,000
Car has issues when downshifting right at 20mph. Goes away if driven for a while and warmed up. Went away for a little while after changing the tranny fluid. Dealership wants to charge me for a diagnostic. Crazy, since this isn't an uncommon issue.
2009 Hyundai Sonata- Automatic Transmission120,000
Same prob as all with slowing to 20 and then hard down shift before stopping when cold. Now at 150000 xmission has loud click and clunk when shift to drive and or reverse. Several different sounds. Runs great other than that. No doubt letting it go was the wrong decision.... I noticed the down shift after replacing the battery. Why would a software prob be costing the customer???? Hmmmm. Still gets 36 mpg. Really didn't want to give a negative comment for just one problem.. Good Luck!
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