Hyundai Sonata jerking problems

Filed Oct 17, 2026 · Transmission · NC

Transmission problems began around 60,000 miles (but we didn’t know what it was) — jerking and hesitation, that worsened over time. We took the vehicle in (November 2025 ),at around 109,000 miles at which time they couldn’t find anything. I took it back in December and they recommended the spark plugs. We took the car back again in March at which time they recommended other little things. We took the vehicle back yet again on March 10 and told them to check the transmission. The dealership said “ As far as the transmission, we cant get it to really do anything so if you dont have an extended warranty we would recommend waiting until the issue gets worse and then put a transmission in it unless you wanted me to get you a price on it”. The vehicle has been at an authorized Hyundai dealership since the third week in June 2026 (because I wanted them to tell me why I had a bad transmission in my three year-old car) while awaiting resolution from manufacturer's consumer advocate (they took 60 days to resolve absolutely nothing). A replacement transmission was authorized on August 6. The manufacturer-supplied replacement was installed and found defective on August 27 (when I asked to test drive the car with a mechanic) it would not shift past 3rd gear. When I asked the dealer why I was not informed, prior to my picking up the vehicle, he told me “we don’t tell the consumer every little thing”. A second replacement was supposedly ordered from the manufacturer August 27, and is still not installed as of October 17. The manufacturer told me “the part was in and being worked on” 10/2. This was false. Th dealership is holding my vehicle hostage and demanding $5,786 for the defective replacement. My vehicle cannot be retrieved. The original transmission that was jerking and hesitating was a hazard to myself and other drivers around me, especially on the highway. The dealer even told me “ this is the third defective manufacturer replacement part received this month”.

Filed Oct 15, 2026 · Brakes, Engine · KY

Vehicle experienced intermittent, severe powertrain defect resulting in a critical safety hazard. Between 30K and 36K miles, the vehicle underwent 3 violent highway deceleration episodes. During these events, the engine began shaking, escalating to violent shaking; with deceleration and coming to a stop, it would shake, then sputter as if it would die. Coming to a complete stop, a total stall was prevented only by the ECM forcing a limp mode lock at 1200 RPMs. When Auto Hold was engaged at this point and my foot was removed from the brake pedal, the mechanical surge caused the vehicle to unexpectedly lurch forward, fighting against and nearly overriding the factory Auto Hold braking safety feature before finally holding. Luckily, no pedestrian was walking in front of my car when this occurred. No check engine light (CEL) or dashboard warning ever illuminated. This safety compromise is directly tied to an ineffective or adjacent remedy involving Service Campaign 9B1 (Opcode 40D219R0) and Safety Recall 286. Under this Opcode, a factory software flash deleted the standard OBD-II trouble code P0451and substituted it with a manufacturer-specific shadow code P14EE00. This software manipulation suppressed universal emission/pressure sensor faults, masking a volatile physical defect within the high pressure fuel delivery and ignition systems. Dealer diagnostics on a running, compromised engine flagged an improper fuel injector pulse and subsequently a failing Cylinder 3 ignition coil. All four injectors were replaced but only one coil, leaving 3 non-updated , factory defective coils in the engine. The vehicle remains an ongoing highway stalling and brake-override hazard due to an incomplete field remedy of a recall-adjacent system. I've filed a Hyundai Complaint with assigned case number 43394228 regarding Safety Recall 286. (Two episodes of the attempted Auto Hold override occurred - first 09/09/2026 and second 09/29/2026.)

Filed Oct 1, 2026 · Engine · CT

"I am filing a complaint regarding severe vehicle jerking, engine surging, and rough transmission shifting immediately following the completion of Hyundai Service Campaign 9C2 (TSB 26-01-013H-1) on my 2015 Hyundai Sonata. The vehicle exhibits dangerous hesitation and lurching during cold starts. This behavior creates a traffic hazard when pulling out of driveways or into intersections during the first 3 minutes of operation. The manufacturer has acknowledged this cold-start defect in an internal 'Drivability Information' memo but has not provided a permanent remedy to repair the software logic."

Filed Sep 23, 2026 · Brakes, Driver assistance · NY

While driving at highway speeds, the emergency brake system will apply and alert me. It’s happened twice now in the last 3 weeks. I’ve experienced a random loss of power while driving on the highway with no check engine light on the dashboard. Lastly, at lower speeds the car will randomly jerk while accelerating with no lights on the dashboard as well. I’ve gone to the dealership but they wanted to charge me a diagnostics fee to first look over the vehicle, which I don’t feel I should be on the hook for since the issue isn’t user caused.

Filed Sep 17, 2026 · Fuel system · 100,000 miles · LA · 1 injury

The contact owns a 2021 Hyundai Sonata. The contact received notification of the federal safety agency Campaign: 25V796000 (Fuel System, Gasoline); however, parts were on back order. The contact stated that while driving at an undisclosed speed, the vehicle jerked with an abnormal gasoline odor inside the vehicle. An unknown warning light was temporarily illuminated. Upon further inspection, the contact became aware that the fuel level had dropped. The vehicle was taken to a local dealer where it was diagnosed with an expanded fuel tank. The contact stated that the O2 sensor, spark plugs, and ignition coils were replaced by a local independent mechanic; however, the failures persisted. The contact had headaches while driving the vehicle. Medical attention was not needed. The manufacturer was made aware of the failure. The failure mileage was approximately 100,000.

Filed Sep 15, 2026 · Transmission · TX

Transmission replaced twice and all of them continue to fail. Several Hyundai service centers are unable to determine the cause and are only able to update/relearn and replace whenever they are able to replicate the issue. The issue is that at a cold start, the car makes a popping sound, jerks and shakes. The car hesitates to accelerate. You can hear the noise of acceleration but RPM does not go past 3 and MPH doesn't go past 30mph. I'm unable to upload docs because of the upload limit. If there's another way to send docs, please let me know

Filed Sep 11, 2026 · Engine, Fuel system · VA

After receiving the Hyundai Service Campaign 9C2 update on my 2015 Hyundai Sonata on XXX, I have started having jerky acceleration when the car is first started and am driving. Also, while driving at highway speed (~65 mph)) and I take my foot off the accelerator to coast, the engine RPM drops suddenly, anywhere from 250 rpm to 750 rpm, then recovers abruptly to where it was at prior to the drop (typically around 2000 rpm). The engine rpm also drops while driving at slower speeds and recovers but is not as noticeable as it is at highway speeds. It was not doing this prior to the Service Campaign. There are no check engine lights or pending codes. I brought it back to the Hyundai dealer and discussed the issue with them on XXX. They acknowledged it was likely due to the Service Campaign and they did not want to keep the car to look at it and said no damage was being done and it was safe to drive. They said a fix was in the works but did not know how long until it was released and I should receive information in the mail on it. Video link [XXX] INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Filed Aug 25, 2026 · Engine · NC

Since I had Service Campaign 9C2 completed, the car hesitates to start, does a mini-lurch upon cold start and runs rough. Two weeks ago, it was put in park, lurched backwards, then died. The starter and battery have been replaced but this has not helped. The car ran fine before this update was done.

Filed Aug 17, 2026 · Transmission · 38,000 miles · AL

The contact owns a 2025 Hyundai Sonata. The contact stated that while the accelerator was depressed, the vehicle hesitated, jerked, and failed to accelerate as intended. The failure occurred while driving from a stop and while driving at various speeds, causing the vehicle to decelerate during the failure. While depressing the brake pedal, there was a rubbing or grinding coming from the vehicle, and the braking was rough. There were no warning lights illuminated. The vehicle was taken to the dealer, who was unable to determine the cause of the failure. The vehicle was not repaired. The manufacturer was not made aware of the issue. The failure mileage was approximately 38,000.

Filed Aug 11, 2026 · Engine · PA

My Sonata 2016 suddenly lit up the Check Engine icon, which was blinking. It is available for inspection request, as it's in the shop right now. Added 2 qts of oil just to be safe. Was hoping the light would go away in the morning. It didn't. The car was sputtering and jerking while I was attempting to get where I was going, so I drove a little slower so it wouldn't stall out, which would have caused someone behind me to crash into me if it stopped suddenly. My mechanic said it was engine failure, possibly due to oil burning. Hyundai Dealer told me there is no recall for this issue, but my mechanic said there had been. I was never notified of such, and when I called them, they said that there was no recall, and she acted like she had never heard of the problem. I find that amazing, since on your website, there are some 717 claims of the same problem.