2017 Kia Optima: misfire or rough idle

Filed Nov 8, 2026 · Engine · NJ

My 2017 Kia Optima LX with the 2.4L Theta II GDI engine has repeated engine misfires caused by oil-fouled spark plugs. The engine burns 1 to 2 quarts of oil every week on only 200 to 250 miles of driving, 4 to 10 quarts per 1,000 miles, far above the 1 quart per 1,000 miles threshold in Kia’s own TSB ENG222. Every time the spark plugs are removed, they are coated with oil. Cylinder #4 has misfired three times in five months (June 5, August, and November 2026), and cylinders #2 and #3 misfired on June 17, 2026. All four ignition coils and spark plugs were replaced in August 2026, and the #4 misfire returned within about three months. We have paid out of pocket for repeated repairs since January 2025. The KSDS update was installed at a Kia dealer. The vehicle is now unsafe to drive because misfires can cause sudden loss of power at highway speed, and running low on oil risks engine bearing damage and seizure. We have taken it out of service. I have written to Kia America’s executives requesting diagnosis under TSB ENG222 and repair under the Theta II settlement’s lifetime warranty. I am asking the federal safety agency to investigate excessive oil consumption and repeated oil-fouled spark plug misfires in Theta II 2.4L GDI engines in 2016–2020 Kia Optimas.

Filed Jul 30, 2025 · Engine, Transmission · GA

Excessive oil consumption started at 61,000 miles, causing engine misfires and dangerous power loss on the road. Engine codes 1326 and P0304 were frequent. Despite numerous services, including sensor replacements, spark plugs and oil top-offs, the problem worsened. At 97,769 miles, the dealer said a full engine replacement is needed along with other pertinent repairs related to the engine are needed. The situation was life-threatening each time as they occurred while driving and I now no working vehicle after my husband's recent death. Kia dealerships acknowledged the defect but refused to replace the engine and advised that Kia Corporate was refusing, although no claim information was ever provided that they indeed contacted the corporate office. I am seeking the federal safety agency support in holding Kia accountable.

Filed Jul 20, 2025 · AR

I previously submitted a report regarding engine failure in my Kia 2017, Optima. I’d like to update the complaint with new details. Upon mechanical inspection, it was confirmed that the engine bears Hyundai branding and has sustained internal damage including broken pistons and valve failure. These issues appear consistent with the known oil ring defect affecting Hyundai-manufactured engines used in Kia vehicles. Symptoms included: Engine knocking and rough idling Sudden loss of oil and reduced performance Full engine failure requiring replacement I believe my vehicle may have been missed in the recall or settlement programs and request this update be added to my case. I’m willing to provide repair estimates, diagnostic reports, and photos upon request. Thank you for investigating this issue further

Filed Jul 7, 2025 · Engine, Transmission · TX

Engine is failing and using over 3 quarts of oil every 700-100 miles. Spark Plugs have become oil fouled and replaced all 4 spark plugs June 11th, 2024 and replaced all 4 spark plugs again January 12th, 2025. Today July 7th, 2025 Check Engine light came back on with Engine Misfire code P0303 Cylinder 3 Misfire, changing spark plugs again today. My safety is put at risk because oil consumption is a know issue with Kia GDI Engines. At any moment my car can run out of oil if it is not check every other week causing my engine to completely fail or a spark plug become Oil fouled and a spark plug needing to be replaced. In July of 2024 when this happened I was on the highway going 70 mph and my car just completed shut down. I could have been seriously injured had I not been able to pull over and only been 5 miles away from my home. I called Kia today to start an Oil Consumption test, stated I am the 2nd owner and while this is a known issue I will pay for and Upper Engine Clean which is only a band aid. This problem has been confirmed with Kia that the GDI Engines are consuming oil. I have also replaced all Engine Coolant, Coolant Temperature Senor, Thermostat as well as the PCV Valve.

Filed Mar 26, 2025 · Engine · DE

I was driving on the highway and randomly my car started to shake very badly and i couldn’t go faster than about 30 mph. My engine light didn’t turn on until i turned the car off and back on after finally making it home after almost getting hit by cars trying to make it back home. I sent it to get looked at and they said that it’s misfiring pretty severely and that kia had a recall on an engine/motor awhile back for my car and to take it to a dealership. I contacted KIA customer care but the only recall I see when I look up my VIN # is for the trunk recall.

Filed Aug 11, 2024 · Acceleration, Engine · OK

The KSDS in my engine is causing engine failure due to the dealership failing to fix the problem when I first experienced stalling, lagging and misfiring of my vehicle, which would often make it shake and I would have to turn the car off and reignite it, sometimes more than once. My safety is at risk when driving, because the vehicle will lag while trying to accelerate in traffic. My mechanic researched the issue and found the recall and Kia said they fixed it when it was issued and they didn’t. My CHECK ENGINE light is flashing now and it continues to lose power. I have contacted Kia about the issue and I’m waiting on a response.

Filed May 19, 2024 · Engine · CA

My 2017 optima is consuming oil into the pistons and piston rings which is soaking the spark plugs causing engine misfire, my mechanic states it wont be long till the engine goes out, I talked to kia and they told me the car has to be seized or knocking for them to replace the engine, knowing its a problem. I want my car fixed as its a known issue across all optimas.

Filed Aug 25, 2022 · Engine · FL

The motor seems to have a knocking noise accompanied by constantly burning oil and sparks plugs. Constant misfires and check engine light appearing during the year after replacing spark plugs and ignition coils.

Filed Apr 8, 2022 · CA

Since I purchased the car I have a had a issue with my vehicle misfiring. We purchased the car in 2018 and a few months in I had to bring the car in for a rattle and shaking while I was driving. It would give me a warning lamp stating that a “possible engine control issue had been found”. Since then I have taken the car in for the same issue three different time. Including the misfire and coil pack and spark plug replacement that I just had to pay nearly 600 for at the dealership. I have had this issue occur multiple time since we purchased the car and while driving on the freeway nearly putting my life at risk. This is an issue that needs to be addressed.