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.
Car Problem Reports
Hyundai Sonata Confirm Latest Software For Transmission Control Module and Correct Fuild For Proper Shift Quailty
Hyundai Sonata Problem
Drive Train Affected: Automatic Transmission
Average Mileage: 49,389 mi (10,000 mi - 96,000 mi)
Visitor, 2010 Hyundai Sonata, Automatic Transmission, 65,000 mi
I noticed that my car is beginning to down shift with a hard thump at 20mph. Has anyone had this problem?
Visitor, 2009 Hyundai Sonata, Automatic Transmission, 71,000 mi
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.
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
Hard 2-1 downshift when the weather got near freezing and the car was cold. Reflash of the computer programming fixed it for awhile. It came back and another reflash and trans fluid change fixed it for good. The trans fluid had been changed 20K earlier but the dealer noted some discoloration so we changed it again. Didn't want to mess around with a more exopensive problem later.
Visitor, 2010 Hyundai Sonata, Automatic Transmission, 43,000 mi
The transmission is hard downshifting into low gear when transmission is cold, quits when running warmed up.
Visitor, 2009 Hyundai Sonata, Automatic Transmission, 96,000 mi
not fixed, I shift into neutral, when coming up to stop signs--Jerky downshift -- if I don't put it in neutral.
Visitor, 2009 Hyundai Sonata, Automatic Transmission, 55,000 mi
Had hard downshift issue around 55k. After a couple of reflashes the ended up putting in a trans. Said the old one wouldn't take the latest update. Now same issue at 120k and the warranty on the new trans expired at 60k with everything else. Haven't taken it in again yet.
Visitor, 2009 Hyundai Sonata, Automatic Transmission, 39,000 mi
Transmission would downshift roughly (or "hard") when slowing down during first 10 minutes or so of driving. Dealer claimed fluid was burnt first time (39K), charged me $200+ to replace fluid. Problem jsut came back again over past few weeks, ~54K, going back to dealer to have it checked again, will likely not pay to have it fixed again there.
Visitor, 2009 Hyundai Sonata, Automatic Transmission, 61,000 mi
When first starts up, downshifts hard-jerky into first gear when slowing down- not fixed
Visitor, 2009 Hyundai Sonata, Automatic Transmission, 59,000 mi
Had a hard shift at about 20 mph when slowing down.
Dealer had service alert to reprogram.
Repaired for no charge.