2018 Kia Optima: engine stalls while driving

Filed Oct 21, 2026 · Engine, Transmission · CA

My 2018 Kia Optima has the Theta II 2.4L engine. In February 2026, the dealer performed an engine/powertrain computer reprogramming. In August 2026, the engine failed and the vehicle was taken to an authorized Kia dealer, where the engine was replaced under the Theta II engine warranty. The vehicle was at the dealer from August 8 until the repair was completed on September 29, 2026. When I picked up the vehicle on October 9, it felt shaky and vibrated on the drive home. On October 11, the vehicle began giving off a distinct, unfamiliar smell that is not like burning fuel or oil. On October 21, I found the vehicle leaking an opaque, milky tan fluid onto my garage floor. The type and source of the fluid are UNKNOWN. I have photos of the leak. My family and I have stopped driving the vehicle because we believe it is unsafe. We were driving it with our children before these symptoms appeared. Given the history of Theta II engine failures, we are concerned about the risk of engine failure, stalling, or fire while driving. The new symptoms have not yet been diagnosed or confirmed by a dealer. I am arranging for the vehicle to be towed to a Kia dealer for warranty diagnosis. The vehicle and leak are available for inspection. I have reported these issues to the manufacturer under an open customer case.

Filed Jun 25, 2026 · Engine · MO

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 out due to the fast burning of the oil, or a potential fire hazard while driving. The oil light will come on for a second and at that point, the oil is already EXTREMELY too low. I brought the car to the mechanic and they have told me multiple times that there is no leak or anything. The mechanic says that the car simply is burning oil too fast.

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.

Filed Mar 18, 2026 · Electrical, Fuel system · FL

I am submitting this complaint regarding ongoing and persistent mechanical issues with my vehicle since the time of purchase. The vehicle has repeatedly shut off unexpectedly, creating a serious safety concern. Initially, I suspected the issue might be related to the battery, and I have replaced the battery twice within the past 4 years. However, the problem has continued. In January, the vehicle began shaking and shutting down again. I took it to a mechanic, who diagnosed the issue as faulty spark plugs and an ignition coil. The diagnostic codes provided were P0303 and P0456, and the recommended repairs were completed. Approximately one month later, the vehicle began shutting off again. I then took it to the dealership, where I was advised that the valve cover gasket needed to be replaced, along with the belts, and that a fuel system cleaning was required. I subsequently had these repairs completed by my mechanic. Less than a week after completing those repairs, the vehicle once again began shutting down. A diagnostic scan then produced code P123300. In addition to these repeated shutdowns, the vehicle consumes an excessive amount of oil, has poor acceleration, and continues to stall unexpectedly both while driving on the road and while idling, such as in a drive thru. These recurring issues have made the vehicle unreliable and unsafe. I am concerned about the risk of the vehicle shutting off while in motion, which could lead to a dangerous situation. I am requesting that this matter be reviewed for potential defects or safety-related concerns.

Filed Dec 10, 2025 · Engine · NM

While driving my 2018 Kia Optima S, the car suddenly jerked, lost power, and stalled in traffic. Multiple warning lights came on at the same time including the oil light, battery light, and check engine light. I had no acceleration and the brakes became very hard to press. The vehicle had to be towed for safety reasons. The Kia dealership inspected the vehicle and confirmed internal engine failure due to “cylinder failure” and stated the engine needs complete replacement. This failure occurred without any external leaks and without warning other than the sudden loss of power. The dealer stated the issue is not covered, even though it is clearly an internal engine malfunction. This is a major safety hazard because the stall happened while I was in active traffic. A sudden loss of power and braking ability puts me and others at risk of an accident. The problem has been confirmed by the Kia dealership through diagnostic testing. The vehicle is still available for inspection. Warning lamps appeared only at the moment of failure, giving no advance warning. This appears to be related to the ongoing engine defects in Kia vehicles involving oil starvation, loss of compression, cylinder scoring, and internal engine failure. Cylinder failure and sudden stalling should be investigated as part of the known safety-related engine defects affecting this model.

Filed Nov 26, 2025 · Engine · LA

Car keeps stalling while driving

Filed May 23, 2025 · Engine · 146,000 miles · TX

The contact owns a 2018 Kia Optima. The contact stated while driving 70 MPH, the vehicle failed to accelerate as intended while depressing the accelerator pedal. The contact turned off the cruise control; however, the failure persisted, and the vehicle stalled. The contact stated that the check oil warning light was illuminated. The contact was able to coast to the side of the road. The vehicle failed to restart, and the vehicle was towed to a service station. The vehicle was then towed to a dealer where it was diagnosed and determined that the high-pressure fuel pump had failed, causing fuel intrusion into the engine and engine failure. The vehicle was not repaired due to the cost. The manufacturer was not made aware of the failure. The failure mileage was approximately 146,000.

Filed Mar 19, 2025 · Engine · 109,000 miles · CA

The contact owns a 2018 Kia Optima. The contact stated that while driving 65 MPH, the check engine warning light illuminated, and the vehicle shuddered and stalled. The contact was able to pull over to the side of the road. The vehicle was able to restart but was shuddering significantly. The vehicle was towed to the dealer, where it was diagnosed with a fractured valve in cylinder #1. The dealer determined that the engine needed to be replaced. The vehicle was not repaired due to the cost. The manufacturer was notified of the failure and confirmed that the maintenance records of the vehicle were satisfactory; however, the manufacturer denied assistance and informed the contact that the failure was not a factory defect but was due to wear and tear. The failure mileage was approximately 109,000.

Filed Feb 25, 2025 · Engine · TN

Complaint-Car misfired, oil leaking on spark plugs causing an Engin Replacement that was first complained to Gossett Kia Covington Pike,1900 Covington Pike, Memphis, Tn 38128 on [XXX].On [XXX] complaint car shakes, misfire. Complaint to Gossett Kia South 2680 Mt.Moriah Rd, Memphis, Tn 35115. This date car stayed at dealership 3 days invoice a diagnostic was performed total amt $913.38. On 12/26/24 Mr.Macias on Mt.Moriah asked me to bring my vehicle in for another diagnostic test, amt to be charged $251.00 this time a tune up, replaced #4 spark plug that had misfired, fuel injectors cleaned I asked Mr.Macias "why would I have that done when it had been done the month before, the Tech recommended Engine Replacement. I also asked the above, what about the Tech's findings, Mr.Macias stated he would get back with me. On 1/16/25 Mr.Macias called to discuss Engine replacement (Projected Amt:$6,300). I have contacted Kia Consumer Assistance on 1/10/25 to discuss all of the above to no avail. I have been without a vehicle since 12/3/26 I am continually getting the run around, I have all invoices to verify my dilemma with a vehicle that is sitting unused. I am a [XXX] who is still making a $484.00 car payment per month. I've done my research on the 2018 Kia Optima's, only to find that the same problem that I'm having with the oil leaking on the spark plugs, misfiring , shaking, causing stalling in the middle of traffic, if this is not a hazard, what is ? This a problem that should have been corrected long ago. I would appreciate it if you would please help me. I'm tired of having to pay to get to and from Dr's. Office visits, drug stores and grocery stores. Thanking you in advance, [XXX] [XXX] or email address : [XXX] INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Filed Jun 28, 2024 · Engine · CA

Engine continuously stalls,while driving in both city and hight way. I have taken it in while under warranty and am told that's just how the car runs. Sudden jerks / seizure will happen while driving. since I haven't gotten the vehicle it happens at min 15mph or on the freeway at 65 mph. It is stalls at all mph .

Filed Apr 22, 2024 · Engine · TX

It started with the car using oil but the mechanic could not determine where the oil was going. It quickly lead to the Cadillac converter going out with a host of other things that cost me over $2900 to fix. Which only lasted a few weeks and the last incident occurred when I was on my way home and it would not pick up speed at all and would stall. The first time it happened I was on the free way and it lost speed almost causing a semi to run into the back of me. The second time I was at a red light and when I tried to accelerate in speed and it stalled and then began to jerk before it would pick up speed. Each time the occurrence happened it placed my life as well as my families life in danger as it was sudden with no engine light or any other lights coming on. The last time it happened it left me stranded with a child, over 2 hours from home and in the middle of the night on isolated highway. Every time I would call KIA they would give me the run around on the issue and say it was due to my negligence but I beg to differ as I feel as if it is an engine error on the manufacturing. Please help. Currently the car is sitting in my yard and I can not afford to keep paying for repairs due to a faulty engine that they refuse to fix.

Filed Feb 8, 2024 · Engine · 82,000 miles · GA

The contact owns a 2018 Kia Optima. The contact stated while driving approximately 40 MPH, the vehicle was losing motive power. The contact stated that there were no warning lights illuminated. The contact stated that the vehicle stalled. The contact was able to stop; however, after numerous attempts to restart the vehicle, the contact had the vehicle towed to the residence. The vehicle was later towed to a local dealer who inspected the vehicle and determined that the engine had seized and needed to be replaced. The contact stated that prior to the stall, the vehicle had been consuming an abnormal amount of engine oil. The contact stated that he was adding a quart of oil every week. The vehicle was not repaired. The manufacturer was informed of the failure. The contact researched online and related the failure to the federal safety agency Campaign Number: 17V224000 (Engine and Engine Cooling). The failure mileage was approximately 82,000.