2015 Hyundai Sonata engine problems

Related recalls

No recalls on file.

What owners say

1. Filed Oct 7, 2026FLEngine

   Ever since the 9C2 software update was completed on 94/26, the car is experiencing hesitations not only in the first few minutes of driving but after the engine is hot. It was driving perfectly before this update.

   NHTSA complaint #11769538 · source
2. Filed Oct 2, 2026NCEngine

   am seeking assistance regarding a sudden and unexpected engine failure with my vehicle. The Sonata only had approximately 80,000 miles on it when the engine failed. Prior to this happening, I had never experienced any problems with the vehicle. There were no warning lights or other indications that there was an issue with the engine, and the vehicle had passed inspection. The engine failure happened completely out of the blue. I have also kept up with the vehicle’s…

   NHTSA complaint #11768632 · source
3. Filed Oct 1, 2026CTEngine

   "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…

   NHTSA complaint #11768229 · source
4. Filed Sep 11, 2026VAEngineFuel, Hybrid & EV Propulsion

   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…

   NHTSA complaint #11763571 · source
5. Filed Sep 10, 2026VAEngineTransmission & Drivetrain

   In March 2026 Hyundai did an emissions update Campaign 9C2. Since that update my 2015 Hyundai Sonata SE has run rough and shifted hard. Hyundai stopped doing the update in May 2026. Hyundai has not provided any update to fix the problem they created. I am worried the update is damaging the motor and transmission of a car that was running just fine prior to the update.

   NHTSA complaint #11763289 · source
6. Filed Sep 1, 2026VAEngine

   The engine failed due to the known recall defect, dealer confirmed loss of compression in cylinders 2 & 4. I am a federal employee stationed overseas on official duty orders, and Hyundai Motor America is delaying safety recall remedies and buyback negotiations since June 9th.

   NHTSA complaint #11761235 · source
7. Filed Aug 27, 2026TXEngine

   Engine locked up, crank bearing failure, found out there is known failures with this problem and Hyundai had a class action suit against them in the past and issued lifetime warranty for this engine due to this problem. Took car to local dealer, Clay Cooley in Sherman TX, they have been great but Hyundai corporate has denied the claim stating lack of maintenance records. Car has 175,000 miles on it, I have only owned it for about 5-6,000 miles. I have changed the oil in it…

   NHTSA complaint #11759964 · source
8. Filed Aug 24, 2026ALEngine

   I bought this car new in 2015, when I was at 97000 miles they had to replace the motor and turbo, I am now at 155844 and they are telling me that basically all 4 cylinders have low compression, cylinder 3 is the worst. They are telling me that this car has to have a new motor. I have not done anything to this vehicle to cause no compression. They want me to pay around 8800.00 to get this fixed.

   NHTSA complaint #11759071 · source
9. Filed Aug 10, 2026MIEngine

   My Hyundai Sonata engine stalled out while driving on the highway. I had it towed to a dealership with the hope they would fix the issue because it was supposed to be covered under warranty from a recall. The dealership said the engine replacement would be covered as long as they got approval from Hyundai. Hyundai apparently only asked that specific dealership for the service records that they had, didn’t even reach out to me or try to find any other service records on the…

   NHTSA complaint #11756074 · source
10. Filed Aug 10, 202688,000 miMIEngine

    The contact owns a 2015 Hyundai Sonata. The contact stated that while driving on several occasions at various speeds, the vehicle lost power, and the check engine warning light was illuminated. The vehicle was taken to a dealer where it was diagnosed that the engine had failed and needed to be replaced. The vehicle was repaired, but the failure reoccurred within a year. The vehicle was taken back to the same dealer where it was diagnosed and determined that a software update…

    NHTSA complaint #11755866 · source
11. Filed Aug 8, 2026FLFireEngine

    Vehicle: 2015 Hyundai Sonata VIN: [XXX] Mileage: ~85,000 Description of the Problem: While driving, the vehicle suddenly began producing thick smoke from under the hood without warning. I safely maneuvered to the shoulder to avoid an accident. The engine subsequently seized completely and became inoperable. My mechanic diagnosed this as a known internal manufacturing defect in the Theta II engine (connecting rod bearing failure), a widely documented issue for this model and…

    NHTSA complaint #11755594 · source
12. Filed Aug 6, 2026MDEngine

    Since the 9C2 update on June 24, 2026, my vehicle has not driven the same. I'm experiencing clunky or harsh gear changes at low speeds, especially during stop-and-go driving. When I slow down and then accelerate again, the vehicle sputters or hesitates before responding. While driving at lower speeds, I also feel intermittent skips or small surges, almost like bubbles or brief misfires. These symptoms were not present before the 9C2 update, and they have noticeably affected…

    NHTSA complaint #11755188 · source

Source: U.S. National Highway Traffic Safety Administration (NHTSA) Office of Defects Investigation public data. Complaints are submitted by owners and are not verified by NHTSA or by us; a complaint does not prove a defect exists. View this vehicle on NHTSA.gov Methodology