2018 Kia Optima engine problems

129 owner complaints filed with NHTSA name the engine on the 2018 Kia Optima — 56% of all complaints for this model year.

129

Engine complaints

56%

share of all complaints

66,000 mi

median reported incident mileage

1 / 9

crash / fire reports

What owners report

“I’ve had my 2018 kia optima for round about two years.I only got this car because they refused to replace my previous engine on my 2015 Kia optima,even though I had a warranty but that’s another story(Kia on the Blvd).This car have given me problems from the start.Going through oil in less than a…”
filed Jul 9, 2026
“The car burns oil within a week of getting an oil change. It was only driven a 200 miles before all of the oil was burned out. This has been a consistent issue with this car that the oil burns at an extreme rate. This is a safety risk as it could lead to engine overheating, the engine could stall…”
filed Jun 25, 2026

Verbatim excerpts from complaints filed with NHTSA. Reports are not independently verified.

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, 2026
VOLUNTARY 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, 2025
TECHNICAL 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