2018 Kia Optima · symptom sheet
Check engine light or misfire
- 37owner reports
- 99,000median miles
- $650median quote
- 0involved a crash
Newest report Jul 9, 2026 · checked Oct 2, 2026
167 of the 232 complaints on this car are about the engine. 37 of those describe misfire.
Tick what matches of 37 reports
Misfire on other Optima years
Report counts are for each model year on its own, so a newer car has had less time to collect them.
What this problem usually is
These reports start with the check engine light. Many describe the engine running rough or shaking at idle, a P0300-series code, or a catalytic converter code. A worrying number say the light was flashing. Owners often list ignition coils or spark plugs already replaced, and the light coming back afterward.
What got replaced
Owners who name the part that was replaced mention the spark plugs (13 reports), the sensor (6 reports) and the ignition coils (3 reports).
Recalls and investigations
No recall on the engine covers the 2018 model year as of Oct 2, 2026.
NHTSA investigations into the engine on the Optima
Loss of motive power. Closed dec 12, 2023.
Engine fires. Closed feb 5, 2024, led to recall 23V-877.
Non-crash vehicle fires. Closed dec 22, 2021, led to recall 20V-088.
Non-crash vehicle fires. Closed may 10, 2019, led to recall 18V-907.
Scope and timeliness. Closed dec 22, 2021, led to recall 17V-224.
What owners paid
5 of the 37 reports quote a price. Each dot is one quote. The middle half runs $484 to $913.
When it happens
The middle half of failures fell between 18,000 and 109,000 miles, from the 16 reports that gave a mileage.
Is this a known problem?
The manufacturer has sent NHTSA 1 service bulletin or notice for the 2018 Kia Optima that deal with this problem. Newest first.
Federal rules make a manufacturer send NHTSA a copy of any notice about a defect that goes to more than one dealer or owner. Most of these are service bulletins, the repair instructions manufacturers send to dealers. NHTSA generally leaves safety recall bulletins out of this file, and recalls are listed separately.
COMBINATION TSB/SERVICE ACTION: AIR FILTER AND NVLD REPLACEMENT (SA421) This bulletin provides the procedure to perform an evaporative leak test and replace the fuel tank air filter, and, if necessary, the Natural Vacuum Leak Detector (NVLD) on some Optima (JF HEV) vehicles, produced from June 27, 2016 through January 7, 2019, ...
What owners wrote
“Car suddenly stopped working; it was struggling to stay on. Mechanic stated cylinder is not functioning at full force.”
Filed Sep 4, 2025
“Got an oil change, and they advised that it was low on oil. (I had just replaced it recently) I took it to the dealer and they advised a part was bad, that they replaced. I was driving and the check engine light and oil light came on . I had to tow car. Dealer said the engine was burning oil, and that the engine is covered, but I would have to drive it until it got worse.”
Filed Jun 15, 2025
“Check engine light began flashing halfway down the highway. Oil changes and maintenance are done regularly. Vehicle handling seemed to be unsafe. Vehicle would not accelerate. Had inspection done in September.”
Filed Nov 25, 2024
“consistently getting oil changes. if the car doesn't rcvd an oil change before 3000 miles the check engine light comes on and then the light removes after oil change. in between the time period of getting oil changes it may run junky or you hear the catalytic converter trying to push air thru and it rattles.”
Filed Apr 30, 2023 · 3,000 miles
Should you keep driving it?
This page can't tell you that. 0 of 37 reports involved a crash. Owners who file are the ones who had a bad experience, and nobody checks their reports. If the problem affects steering, braking, power or a fire risk, treat it as a safety fault and have it inspected before a long or high-speed drive.
File your own report with NHTSA. Complaint counts are how a problem gets an investigation. How reports land on this sheet.
Guide Which lights mean pull over now? Warning lights by color and urgency
Other problems on this car
- Engine failure, knocking or rod bearing 52 reports
- Burns oil or oil level rises 48 reports
- Engine stalls or loses power while driving 34 reports