2015 Hyundai Sonata engine problems
623 owner complaints filed with NHTSA name the engine on the 2015 Hyundai Sonata — 54% of all complaints for this model year.
What owners report
“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…”
filed Sep 11, 2026
“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…”
filed Sep 10, 2026
“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.”
filed Sep 1, 2026
Verbatim excerpts from complaints filed with NHTSA. Reports are not independently verified.
Related service bulletins
Certain Santa Fe (TMA), Santa Fe Sport (AN), Sonata (LFA), and Tucson (TL) vehicles equipped with Theta II engines may exhibit elevated engine-out emissions. This bulletin provides instructions for updating the Engine…
26-01-013H-2 TSB · Service Campaign · issued May 21, 2026Some vehicles may exhibit difficulty starting in cold weather. This bulletin provides the procedure to perform an inspection on the starter magnetic switch for potential freezing and, if necessary, replace the starter…
26-EE-003H TSB · Service Bulletin/Repair Instructions · issued Apr 18, 2026Certain 2019 – 2020 model year Santa Fe, 2017 – 2018 model year Santa Fe Sport, 2015 – 2019 model year Sonata, and 2018 – 2021 model year Tucson vehicles may exhibit elevated engine-out emissions. Hyundai is conducting…
9C2 OL · Service Campaign · issued Apr 14, 2026
Engine problems in other Sonata years
| Year | Reports | Share |
|---|---|---|
| 2024 Sonata | 3 | 7% |
| 2023 Sonata | 27 | 31% |
| 2022 Sonata | 25 | 27% |
| 2021 Sonata | 34 | 26% |
| 2020 Sonata | 31 | 17% |
| 2019 Sonata | 86 | 53% |
| 2018 Sonata | 210 | 56% |
| 2017 Sonata | 383 | 50% |
| 2016 Sonata | 450 | 62% |
| 2014 Sonata | 301 | 40% |
| 2013 Sonata | 735 | 39% |
| 2012 Sonata | 567 | 36% |
Other reported problem areas on the 2015 Hyundai Sonata
Counts are unique NHTSA complaints naming this component group. Complaints are unverified owner reports; mileage is computed only from complaints that included a usable odometer reading.