2018 Hyundai Sonata engine problems
210 owner complaints filed with NHTSA name the engine on the 2018 Hyundai Sonata — 56% of all complaints for this model year.
What owners report
“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 25, 2026
“The paint on all parts of the car is completely coming off down to bare metal. It’s as if the car wasn’t prepped to receive paint. Every Hyundai I pass that’s white the paint is coming off. There is also an internal engine oil leak where I’m losing 4qts of oil a week.”
filed Aug 16, 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. The California Air Resources Board has determined that these…
26-01-013H-2 DN · 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% |
| 2017 Sonata | 383 | 50% |
| 2016 Sonata | 450 | 62% |
| 2015 Sonata | 623 | 54% |
| 2014 Sonata | 301 | 40% |
| 2013 Sonata | 735 | 39% |
| 2012 Sonata | 567 | 36% |
Other reported problem areas on the 2018 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.