2018 Kia Optima engine problems
131 owner complaints filed with NHTSA name the engine on the 2018 Kia Optima — 56% of all complaints for this model year.
What owners report
“The contact owns a 2018 Kia Optima. The contact stated that upon starting the vehicle, the vehicle jerked abnormally. The failure persisted while driving, and the vehicle lost motive power. The contact was able to restart the vehicle; however, the failure persisted while driving. The vehicle was…”
filed Sep 8, 2026
“The contact owns a 2018 Kia Optima. The contact stated that while driving at an undisclosed speed, the vehicle failed to accelerate and failed to exceed 52 MPH. The vehicle shut off. The contact stated that the engine was running rough while stationary and the vehicle shut off without warning. The…”
filed Aug 20, 2026
Verbatim excerpts from complaints filed with NHTSA. Reports are not independently verified.
Related service bulletins
VOLUNTARY EMISSIONS SERVICE CAMPAIGN: THETA II 2.4L GDI EMISSIONS: ECM LOGIC IMPROVEMENT (SC340 REVISION 5) - This bulletin has been revised to include additional information. New/revised sections of this bulletin are…
SC340_TSB_R5 · Emissions · issued Apr 4, 2026VOLUNTARY EMISSIONS SERVICE CAMPAIGN: OWNER NOTIFICATION (SC340 FLIGHT 103 / JF) - This document is the owner notification advising that Kia is conducting a Voluntary Emissions Service Campaign to improve the emissions…
SC340_OWNR_JF103 · Emissions · issued Dec 19, 2025TECHNICAL SERVICE BULLETIN: VOLUNTARY EMISSIONS SERVICE CAMPAIGN: THETA II 2.4L GDI EMISSIONS ECM LOGIC IMPROVEMENT (SC340) - This bulletin has been revised to include additional information. New/revised sections of…
SC340_TSB_R3 · Service Bulletin/Repair Instructions · issued Dec 10, 2025
Engine problems in other Optima years
| Year | Reports | Share |
|---|---|---|
| 2020 Optima | 98 | 68% |
| 2019 Optima | 88 | 43% |
| 2017 Optima | 164 | 64% |
| 2016 Optima | 424 | 56% |
| 2015 Optima | 622 | 62% |
| 2014 Optima | 283 | 48% |
| 2013 Optima | 612 | 44% |
| 2012 Optima | 398 | 43% |
| 2011 Optima | 256 | 43% |
| 2010 Optima | 9 | 12% |
| 2009 Optima | 14 | 12% |
| 2008 Optima | 19 | 13% |
Other reported problem areas on the 2018 Kia Optima
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.