Kia Optima misfire problems

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 3, 2026 · TN

Code was on and off for a cylinder 2 misfire was off at this point (intermittent misfire) ecl was off car stalled out at 3rpms while driving, tiny puff of smoke once came from between the air intake and the engine, and also no crank no start but car has power. I’ve kept up with the oil changes every 3000 miles car had fluids in it and nothing looked bad all 4 spark plugs were burnt and i replaced them and still no success.

Filed Jul 2, 2026 · GA · fire

I had just stopped at stop sign and I turned right. My speed was approximately 40 mph and there was a LOUD POP. I immediately hit the brakes and had NO BRAKES. I got car off road and smoke was already coming from under hood. It caught fire immediately and burned up. Total loss . About 6 months prior to it burning I had a good bit of front end work done on it with bearing issues. Also put a new set of tires at same time . The coils and plugs were changed often because it would misfire. I purchased car July 2025. All my documents were burnt also .

Filed Jun 16, 2026 · Engine, Fuel system · CA

My 2016 Kia Optima equipped with the 2.4L DOHC I4 GDI engine began to experience progressive and severe oil consumption during the latter part of my ownership. The oil warning light began activating repeatedly, even after shortly getting the oil changed. Several certified mechanics and oil change service stations told me this was an ongoing issue with this car and engine and that there was nothing I could do but monitor it and keep it filled. At their instruction, I monitored and had it changed more frequently, often topping it off at the oil change station and at home when needed. Approximately 2 weeks after an oil change upon putting the car in reverse it started to shake uncontrollably. The car was towed to a mechanic who stated I needed an engine. I then towed it to an authorized Kia franchise dealership where the technician documented the oil consumption complaint, confirmed a Cylinder 2 misfire code, performed a borescope inspection, and found the Cylinder 2 exhaust valve burnt with a chunk missing. Engine replacement was recommended by the Kia dealership technician. Prior to my purchase, the engine had already been replaced at approximately 80,000 miles under recall-related circumstances. The replacement engine installed by a Kia dealership subsequently failed, exhibiting symptoms consistent with the documented widespread defect affecting the 2.4L DOHC I4 GDI engine in 2016 Kia Optima vehicles, including severe oil consumption, cylinder misfire, and catastrophic internal engine damage confirmed via borescope at a Kia franchise dealership. Kia America denied the claim based solely on mileage despite the damage being confirmed by their franchise technician. My vehicle became unsafe to drive due to this engine instability shortly after starting before becoming fully inoperable. My vehicle has been non-operational for approximately 5 months. Kia has not provided a substantive written determination despite a formal written demand submitted in March 2026.

Filed Jun 8, 2026 · Engine, Fuel system · TX

The car returned P1326 and had multiple misfires and audible knocking, the dealers will indeed fight the already existing class action warranties. Was sent home and told to “drive the fuck out of it”, to which the car did not make it home and blew gasoline into my cabin while driving on the highway. Almost passed out, and am still fighting Kia to actually address the defective rod bearings. I personally would fight tooth and nail over a 5 dollar problem, but this is something they do nationwide and can cause serious injury or death. If it weren’t a 200 LB man driving the gasoline shooting into the cabin would absolutely cause a knockout. To the time of this report they are still trying to disregard the rod bearing issue and send me home with fixes to problems caused consequentially.

Filed May 15, 2026 · Engine, Transmission · AR

Issue 1: High oil consumption in the engine due to poor engine design, according to the auto repair center. 5 quarts of oil are added to the engine once every 2-3 weeks. All oil leaks were previously repaired, but oil is still burning off. Issue 2: The engine has misfired more than once, with a puff of smoke coming out of the exhaust. Issue 3: Twice in the past 1.5-2 years, multiple spark plugs have failed, causing a breakdown. This is a Theta II engine, but it is not in the class action settlement.

Filed Apr 30, 2026 · Electrical, Engine · GA

A issue with the Valve cover gasket leaking into the engine causing a misfire. Making the car suddenly stop while driving which is very unsafe. I took the car to the dealership and they want to charge me for the repairs. I have 2 kia optima hybrid and both cars have the same issue around the same mileage. There were no warning lights during the time it was at the shop. However one day the check engine light did come on and the OBD code P1326 came up. When I took it to the shop the check engine light disappeared and the dealership said they will not check my engine unless they see the code on their end. I believe later down the line the engine will stall out and it should be fixed now while under warranty. However I received no help from the dealership unless I am willing to pay upfront. In addition to this there are electrical issues the front seats aren't moving immediately when the button is pressed. The steering wheel buttons barely work along with the radio. This is a huge problem that needs to be fixed.

Filed Apr 30, 2026 · Engine, Transmission · KY

Sudden engine failure while driving with no warning. Vehicle began jerking, shaking, and losing power. RPMs dropped unexpectedly and the engine stalled intermittently. Multiple misfire codes were present (cylinders 1, 3, and 4), and the engine was found to have low or no compression in cylinder 1. The condition rapidly worsened to near complete engine failure. The vehicle was operating normally prior to this incident. This failure is consistent with known Kia engine defects involving internal engine damage, including rod bearing failure. This is a safety concern due to sudden loss of power while driving.

Filed Apr 30, 2026 · Electrical, Engine · GA

Code : P1777 Transmission- oil pump A issue with the Valve cover gasket leaking into the engine causing a misfire. Making the car suddenly stop while driving which is very unsafe. I took the car to the dealership and they want to charge me for the repairs. I have 2 kia optima hybrid and both cars have the same issue around the same mileage. There were no warning lights during the time it was at the shop. I believe later down the line the engine will stall out and it should be fixed now while under warranty. However I received no help from the dealership unless I am willing to pay upfront. In addition to this there are electrical issues the front seats aren't moving immediately when the button is pressed. The steering wheel buttons barely work along with the radio. This is a huge problem that needs to be fixed.

Filed Apr 28, 2026 · Engine · VA

2018 Kia Optima LX, 2.4L GDI Theta II engine. Approximately 128,000 miles. Reporting severe internal oil consumption that has progressed to engine misfire and shaking, consistent with late-stage Theta II connecting rod bearing failure. The vehicle is now unsafe to drive and has been parked. Timeline: Purchased as a Certified Pre-Owned vehicle in December 2021. Excessive oil consumption began shortly after purchase. For approximately 4.5 years I have added about 1 quart of oil every 2 weeks to keep the engine from running dry. No external leaks have ever been found by any mechanic. Multiple independent mechanics attempted diagnosis and repair over this period. None resolved the issue. The vehicle has now developed a pronounced shake and apparent engine misfire, the textbook progression to rod bearing failure documented in the federal safety agency investigation PE19-004 and prior recalls/campaigns 17V‑224, SC147, and SC172. Safety concerns: Sudden engine seizure or stall at highway speed creates a serious crash risk for me and surrounding traffic. Theta II 2.4L GDI rod bearing failure has been associated with under-hood fires. The defect develops gradually with no warning to the driver beyond elevated oil consumption, which is frequently dismissed as normal until catastrophic failure occurs. I am filing this complaint to document the failure and to add to the federal safety agency's data on the Theta II GDI 2.4L engine in 2018–2019 Optimas. This model year was excluded from the original 2017 recall but is included in the Hyundai and Kia Engine Litigation class settlement and the lifetime engine warranty extension. My vehicle's symptoms match the defect pattern exactly. I will pursue warranty engine replacement, but I want this safety failure on the federal record regardless of how Kia responds.