652 of the
1,400 complaints about the 2015 KIA Optima are about the
engine — 47% of everything
reported for this model year.
Half of the failures with a mileage on record happened before
88,000 miles.
The contact owns a 2015 Kia Optima. The contact stated that for over 8 years, the vehicle was experiencing excessive oil consumption. There was no warning light illuminated. The contact became aware that there was an oil leak on the ground underneath the vehicle. The vehicle was taken to the dealer on several occasions for the oil consumption failure; however, the dealer was unable to find a fault with the vehicle. The dealer had not yet provided a cause for the oil leak. The vehicle was not repaired. The manufacturer was notified of the failure. The failure mileage was 123,000.
NHTSA complaint #11758211 — an unverified report by a vehicle owner.
Austell, GA
ENGINE
The engine in my vehicle failed while putting the car into reverse to back into my garage. I thank God I wasn't on the road when this happened. I took the car into a mechanic who confirmed that the engine was locked and that the car was very low on oil(even though I had my oil changed by him a few months prior). There was an undetected oil leak that led to the engine failure. The warning indicators didn't appear on my dash until after my engine failed.
NHTSA complaint #11758113 — an unverified report by a vehicle owner.
Brockton, MA
ENGINE
This is a formal vehicle safety complaint regarding a manufacturer's active refusal to remedy a known safety defect under an active recall campaign guidelines.My 2015 Kia Optima Turbo experienced an active internal mechanical engine knock, violent sputtering, and a complete engine seizure. The vehicle is currently sitting un-driveable at an authorized Kia dealership.The required Knock Sensor Detection System (KSDS) software update was successfully completed on this vehicle prior to the incident, legally qualifying it for a 100% free long-block engine replacement under the manufacturer's active Lifetime Warranty extension. However, the dealership service department is actively withholding the safety warranty paperwork and refusing to submit the diagnostic photos and engine seizure data to corporate for warranty approval unless I agree to pay an additional $800 out of pocket for an external throttle body and O2 sensor.I have explicitly declined the retail accessory charges five separate times. I only authorize the replacement of my front sway bar links. Instead of separating the ticket and processing the free engine block safety remedy, the dealer is holding my safety warranty hostage to force a retail sale. Furthermore, a manufacturer consumer care representative recently refused to listen to my request on this matter and dropped the call.The manufacturer is using internal technical advice to block a court-ordered safety remedy and is allowing a dealership to use unauthorized retail accessory charges to deny me a safe, operating vehicle. I request immediate federal intervention to force the manufacturer to release the free engine block safety replacement order to the dealer and halt these predatory dealer practices.
NHTSA complaint #11756632 — an unverified report by a vehicle owner.
at 140,000 milesGroton, CTFire
ENGINE AND ENGINE COOLING
The contact owns a 2015 Kia Optima. The contact stated that while driving at an undisclosed speed, the vehicle stalled. During the failure, several unknown warning lights flashed on the instrument panel and there was smoke coming from under the hood of the vehicle. The contact exited the vehicle, and there were flames coming from underneath the hood. The Fire Department was called to the scene and extinguished the flames. During the failure, the vehicle was destroyed. A Police report was filed, and the vehicle was towed to a tow lot. The cause of the failure was not yet determined. The manufacturer was notified of the failure. The contact stated that the original engine was previously replaced by the local dealer due to a previous recall. No further information was available. The failure mileage was 140,000.
NHTSA complaint #11752336 — an unverified report by a vehicle owner.
Woodbridge, VA
ENGINE
My girlfriend was driving on interstate 95 to pick me up from the metro. The engine suddenly cut off in a manner that appears to have melted the wiring harness of the vehicle, risking fire. She was able to safely get to the side of the road and call a tow. After taking it to a local repair shop, they diagnosed the issue as related to the KSDS recall. We had it towed to the dealership that has also confirmed it is related to the recall. The engine is completely seized following this incident and it's worth noting that Kia is completely denying the engine repair claim as the KSDS update was not installed prior.
NHTSA complaint #11751632 — an unverified report by a vehicle owner.
at 212,000 milesBowie, MDFire
ENGINE AND ENGINE COOLING
The contact owned a 2015 Kia Optima. The contact stated that while driving to the residence, the vehicle caught on fire. The contact stated that while at a traffic light, the vehicle suddenly shut off. After exiting the vehicle, the hood was opened, and there was smoke coming from the engine compartment. The contact called an independent mechanic and, within two minutes, became aware of the fire. The contact called 911 for the Emergency Services. The Fire Department arrived and extinguished the fire. There was no injury sustained. There were no warning lights illuminated. The vehicle was previously taken to an unknown local dealer, where it was diagnosed that the engine was leaking with a blown head gasket. The engine was replaced. The vehicle was towed from the scene and was deemed a total loss by the insurance company. The manufacturer was contacted and opened a case. The failure mileage was approximately 212,000.
NHTSA complaint #11750336 — an unverified report by a vehicle owner.
Okmulgee, OK
ENGINE
While driving my 2015 Kia Optima, the engine failed completely without warning. The vehicle lost power while in motion approximately 300 miles away from my home. All warning lights illuminated and the car shut down during driving conditions, creating a serious safety hazard. The vehicle was towed to a Kia dealership where it was inspected. I was informed the engine has failed and may be related to the known 2.4L engine defect and prior recall campaign involving this engine type. This vehicle has a history of multiple recalls, including engine-related recalls issued in 2018 for the same engine family. The failure occurred suddenly and without prior adequate warning, and the vehicle is now inoperable. I purchased the vehicle in May 2023, and at the time of failure it had approximately 133,000 miles. The engine began knocking loudly prior to failure, then stalled and shut off completely while driving. This incident placed me and others at risk because the vehicle lost propulsion while in traffic. I believe this may be related to a known manufacturing defect in Kia 2.4L engines that has been the subject of recall and/or investigation. I am requesting that this complaint be documented as a safety-related engine failure potentially associated with the existing recall and that it be reviewed for further investigation and manufacturer accountability
NHTSA complaint #11745917 — an unverified report by a vehicle owner.
Artesia, CA
ENGINE
1. What component or system failed or malfunctioned, and is it available for inspection upon request? The primary failure involved the engine. The vehicle experienced a major engine failure that resulted in an engine replacement under a manufacturer recall. After the replacement engine was installed, the vehicle later developed additional engine-related problems. An independent mechanic advised that the vehicle would require another engine replacement or extensive engine repairs. Additional defects included a malfunctioning moonroof that would no longer close properly and other mechanical issues affecting the vehicle's operation. The vehicle may be available for inspection depending on its current status and location. 2. How was your safety or the safety of others put at risk? The repeated engine problems created concerns about the reliability and safe operation of the vehicle. Sudden engine failure while driving resulted in loss of power, inability to maintain speed in traffic, and being stranded in unsafe conditions. The ongoing mechanical failures caused significant concern regarding the vehicle's dependability and safety. 3. Has the problem been reproduced or confirmed by a dealer or independent service center? Yes. The original engine issue was confirmed by authorized service personnel and resulted in an engine replacement under a manufacturer recall. The subsequent engine-related problem was evaluated by an independent mechanic, who advised that the vehicle required another engine replacement or significant repairs. 4. Has the vehicle or component been inspected by the manufacturer, police, insurance representatives, or others? The vehicle was inspected in connection with the original engine recall and replacement. It was also inspected by an independent mechanic regarding the subsequent engine issues. At this time, I am not aware of any inspection by police or insurance representatives related to these mechanical failures. 5. yes, right away
NHTSA complaint #11745534 — an unverified report by a vehicle owner.
Phoenix, AZ
ENGINE
P1326 code flashing engine light knock sensor went out 3 times in 6 months and just replaced it again and this time engine light didn't go off I was reading that there was a recall on this but apparently mine doesn't state it. Car cannot pass emissions if engine light is on and the 15th of June is approaching. The car doesn't make any sounds or nothing.
NHTSA complaint #11742779 — an unverified report by a vehicle owner.
at 137,000 milesUnion Springs, AL
ENGINE
The contact owns a 2015 Kia Optima. The contact received notification of NHTSA Campaign Number: 21V331000 (Service Brakes, Hydraulic); however, the part to do the recall repair was unavailable. The contact stated that the manufacturer had exceeded a reasonable amount of time for the recall repair. The contact stated that while starting the vehicle, the check engine warning light illuminated. The vehicle was take to O'Reilly's to be diagnosed. The DTC: P1326; was retrieved. The contact attempted to start the vehicle, but the vehicle failed to start. The contact researched online and found NHTSA Campaign Number: 20V543000 (Service Brakes, Hydraulic). The dealer was contacted, and it was confirmed that the vehicle was included in NHTSA Campaign Number: 20V543000 (Service Brakes, Hydraulic); however, the dealer refused to repair the vehicle because the vehicle was not currently registered and additional repairs were needed before a recall repair could be performed. The vehicle was being towed to the dealer. The vehicle was not yet repaired. The manufacturer was made aware of the issue. The failure mileage was approximately 137,000.
NHTSA complaint #11742315 — an unverified report by a vehicle owner.
at 60,000 milesCarbondale, ILFire
ENGINE AND ENGINE COOLING
The contact owns a 2015 Kia Optima. The contact stated that while accelerating at 55 MPH, there was an abnormal burning smell detected. While driving, she was alerted by another driver who informed her that the vehicle was on fire. The passengers were able to exit the vehicle safely. The vehicle was engulfed in flames. There were no reported injuries. The vehicle was towed to a tow lot. The vehicle was previously taken to an independent mechanic, who said the engine was bad. The engine was previously replaced at 147,000 miles. The fire department was able to extinguish the fire. A police report was filed. The local dealer was not contacted. The vehicle was not diagnosed or repaired. The manufacturer was contacted, but no assistance was provided. The failure mileage was approximately 60,000.
NHTSA complaint #11740785 — an unverified report by a vehicle owner.
at 60,000 milesCarbondale, ILFire
ENGINE
The contact owns a 2015 Kia Optima. The contact stated that while accelerating at 55 MPH, there was an abnormal burning smell detected. While driving, she was alerted by another driver who informed her that the vehicle was on fire. The passengers were able to exit the vehicle safely. The vehicle was engulfed in flames. There were no reported injuries. The vehicle was towed to a tow lot. The vehicle was previously taken to an independent mechanic, who said the engine was bad. The engine was previously replaced at 147,000 miles. The fire department was able to extinguish the fire. A police report was filed. The local dealer was not contacted. The vehicle was not diagnosed or repaired. The manufacturer was contacted, but no assistance was provided. The failure mileage was approximately 60,000.
NHTSA complaint #11740785 — an unverified report by a vehicle owner.
at 75,309 milesIndianapolis, INFire
ENGINE
The contact owned a 2015 Kia Optima. The contact stated that while driving at 65 mph and slowing down to enter a parking garage, she observed black smoke emanating from under the hood, and the vehicle stalled. The contact then observed flames near the windshield wipers coming from under the hood of the vehicle. The contact exited the vehicle and called 911. She observed flames coming from under the hood and under the vehicle, and the vehicle became engulfed in flames. The contact stated that the garage manager attempted to extinguish the fire but was unsuccessful. The police and fire department arrived shortly after the attempt, and the fire department extinguished the fire. The contact did not sustain any injuries. A police report was not taken, and she was not aware of any fire department report being filed. The vehicle was bulldozed out of the parking garage and towed to a tow yard. The manufacturer was notified of the failure, and a complaint was filed. The failure mileage was 75,309.
NHTSA complaint #11738851 — an unverified report by a vehicle owner.
Woodlawn, VA
ENGINE
Was driving down the interstate and the engine lost some power and the engine blew and parts of the connecting rod was on the outside of motor which blew a hole in the block and oil went into the intake manifold and pieces of the piston ring was in there and engine shut off, and seen that this has been a problem with these cars
NHTSA complaint #11736696 — an unverified report by a vehicle owner.
Bechtelsville, PA
ENGINE
Engine seized while driving.
NHTSA complaint #11731047 — an unverified report by a vehicle owner.
Irving, TX
ENGINE
Was driving then suddenly the engine shut off I was able to pull to the side Tried to restart it I saw smoke coming out from the hood I did tow it to my apartment looks like the engine is locked I contacted kia they said I have a branded title they can’t do anything about it Even if the car title was branded to a rear ending collision And the engine had oil in it
NHTSA complaint #11725883 — an unverified report by a vehicle owner.
at 174,000 milesMemphis, TNFire
ENGINE
The contact owned a 2015 Kia Optima. The contact stated that while driving at 60 MPH, during a DoorDash delivery, the vehicle vibrated. The contact pulled to the side of the road and noticed smoke emitting underneath the vehicle from the right side. The contact exited the vehicle and noticed smoke emitting from underneath the hood. The state troopers were called. By the time the fire department arrived, the vehicle was engulfed in flames, and the engine had exploded. The fire department extinguished the fire. The contact was not injured. No police report was filed. The state troopers believed that the fire was caused by an electrical short. The contact stated that prior to the fire, the vehicle vibrated when idled. No warning lights were illuminated. The vehicle was towed to a towing yard. The insurance company was not notified about the fire. The contact was unaware that NHTSA Campaign Number: 21V331000 (SERVICE BRAKES, HYDRAULIC) was associated with the VIN. The manufacturer was not notified of the fire. The failure mileage was approximately 174,000.
NHTSA complaint #11725022 — an unverified report by a vehicle owner.
at 124,000 milesPhiladelphia, PA
ENGINE AND ENGINE COOLING
The contact owns a 2015 Kia Optima. The contact stated that while driving at 40 MPH, there was smoke coming from underneath the hood, and the engine overheated. The check engine warning light was illuminated. The contact was able to pull over to the side of the road and add coolant to the coolant reservoir. The vehicle slowly started and was driven to the destination. The contact stated that the engine was overheating if driven for more than 10 minutes. The vehicle was taken to an independent mechanic, where it was determined that the vehicle was experiencing excessive coolant consumption, and coolant was added as needed. The mechanic determined that the failure might be related to the engine. The vehicle failed to start and was undrivable. The vehicle was not repaired. The dealer was contacted and referred the contact to the manufacturer for assistance. The manufacturer was contacted, and a case was filed. The failure mileage was approximately 124,000.
NHTSA complaint #11721647 — an unverified report by a vehicle owner.
Rio Rancho, NM
ENGINE
On Friday, February 27, 2026. This vehicle is being driven and vehicle seized and disabled on the road. In the middle of rush hour, traffic in a dangerous spot, local police had to be called out to assist, as no location was identified for a tow truck to be able to pick it up... The police had to dispatch their own tow service. After being towed from location where a car was disabled, mechanic looked at vehicle identifying there was no oil in the car. However on, September 9, 2025 an oil change was performed on the vehicle at 139,969 the car seized at 143,369.. That is approximately 3,399 miles driven from the time of the oil change up until the time it seized... There was no indicator lights that ever identified that an oil change was needed or low on oil on the vehicle prior to the car disabling..
NHTSA complaint #11721582 — an unverified report by a vehicle owner.
Jay, FL
ENGINE
The vehicle started making a loud knocking/tapping noise while driving. The vehicle has randomly acted as if it was going to stall while driving prior to the knocking. Instantly the car was brought home and parked. A mechanic has assessed the vehicle and states the noise we are hearing is the rods. We also contacted another mechanic and they advised us to look up the VIN due to a recall for 2015 Kia optima’s and the failure of this exact issue but we learned it was only for hybrid models even though this model has had the same exact issues as that model. I then see there have already been complaints made for my same issue and model yet no recall campaign has been initiated. I am fearful to drive or try to sell this vehicle because what if someone else drives it and it does stall again during driving and injury or death occurs.
NHTSA complaint #11720091 — an unverified report by a vehicle owner.
Los Angeles, CA
ENGINE
Engine failure while driving on freeway. Almost hit by semi truck. Towed to Dealership. Engine check light flashing complete loss of power. Kia refusing engine replacement under settlement.
NHTSA complaint #11719695 — an unverified report by a vehicle owner.
Eden Prairie, MN
ENGINE
Engine seized and won’t turn at all
NHTSA complaint #11719754 — an unverified report by a vehicle owner.
Concord, CA
ENGINE
On December 27, 2025, at approximately 150,556 miles, my 2015 Kia Optima Hybrid experienced sudden engine knocking, power loss, and failure while driving at 65 mph on a highway. The vehicle dropped into limp mode and I had to pull off the highway. The car required towing to the dealership as it would not drive safely. Diagnostics revealed a knock sensor error (P1326 code) and failing connecting rod bearings via Bearing Clearance Test, consistent with the known Theta II engine defect (manufacturing debris causing oil starvation and premature bearing wear). This follows earlier symptoms: Intermittent 'Check Hybrid System' warnings in early December 2025 at 148,665 miles (dealership unable to reproduce, but historical codes noted). The Knock Sensor Detection System (KSDS) software update was performed in February 2022 during prior CHS warnings. Despite onset of issues under the 150,000-mile extended warranty limit per the Kia E2 Settlement, Kia denied coverage due to the minor mileage overage and directed me in a loop between Consumer Assistance and the Settlement Administrator. The defect poses a serious safety risk: potential for sudden engine seizure, stalling while driving, or engine compartment fire (as seen in related Theta II recalls and thousands of NHTSA complaints). No crash, injury, or fire occurred in my case, but the failure left the vehicle undrivable and unsafe on the road. I have service records and diagnostic reports to support this.
NHTSA complaint #11717931 — an unverified report by a vehicle owner.
Holmen, WI
ENGINE
Valve cover leaking and oil dripping oil on exhaust at 114k miles. Risk of engine fire.
NHTSA complaint #11716870 — an unverified report by a vehicle owner.
at 96,000 milesFort Pierce, FL
ENGINE
The contact owns a 2015 Kia Optima. The contact stated that while driving at an undisclosed speed, the engine seized, and the vehicle stalled. The vehicle was able to coast to the side of the road. The check engine warning light and several other warning lights were illuminated. The contact raised the hood, and there was a burning odor coming from the engine. The vehicle was towed to the place of employment. A mobile mechanic arrived at the place of employment and used a handheld code reader to diagnose the vehicle, but no DTC was retrieved, and no cause for the failure was determined. The starter was replaced; however, the vehicle failed to restart. The vehicle was towed to an independent mechanic, who diagnosed that the engine had failed and needed to be replaced. The vehicle was not repaired due to the cost. The contact stated that the vehicle was purchased six months prior to the failure. The manufacturer was not made aware of the failure. The failure mileage was approximately 96,000.
NHTSA complaint #11714265 — an unverified report by a vehicle owner.
Pacific, MO
ENGINE
I've had car for not very long and rid bearings now all of a sudden went out and engine is bad at this point and don't understand why my vehicle wouldn't be included in all the different recalls for 2015 optima because it's one of the years of theta 2 engine being recalled and mine says 0 recalls why is that?
NHTSA complaint #11713208 — an unverified report by a vehicle owner.
Delano, CA
ENGINE
Engine seized
NHTSA complaint #11709557 — an unverified report by a vehicle owner.
at 53,000 milesColumbus, OHFire
ENGINE
The contact owned a 2015 Kia Optima. The contact stated that while driving at 55 MPH, while depressing the accelerator pedal, the contact could smell a burning smell within the vehicle, and then he noticed smoke coming from the front of the vehicle. No warning lights illuminated. The contact pulled over to the right side of the road and exited the vehicle, opened the hood, and noticed smoke and flames coming from the engine. The contact exited the vehicle and stood on the side of the road, and called 911. No injuries were sustained. No medical attention was required. The contact mentioned the police showed up on the scene; however, he could not remember if he received a police report. A fire department report was filed. The fire department extinguished the fire. The vehicle was destroyed. The vehicle was towed to Pro-Cars. The vehicle was not repaired. The contact mentioned he contacted his insurance company, and they informed him that the vehicle was a total loss. The manufacturer was notified of the failure, and they transferred him to the escalation department and informed him that an inspector would inspect the vehicle, and he had to wait seven to ten business days for a resolution. The failure mileage was 53,000.
NHTSA complaint #11705972 — an unverified report by a vehicle owner.
Houston, TX
ENGINE
The engine in my 2015 Kia Optima suddenly seized due to connecting rod bearing failure at approximately 55,000 miles. This vehicle is known to be affected by the Theta II engine defect. I was never aware of the seriousness of the recall software update and did not receive meaningful notice that failure to install it could result in catastrophic engine failure. Kia has denied engine warranty coverage solely because the software update was not installed prior to failure, despite the defect existing regardless of software.
NHTSA complaint #11705421 — an unverified report by a vehicle owner.
Delano, CA
ENGINE
My 2015 Kia Optima (VIN [XXX] ) experienced sudden engine failure and stalled while driving at approximately 90,000 miles. There was no oil pressure warning light and no knocking prior to failure. The check engine light illuminated shortly before the stall. Kia is denying engine coverage solely because an ECU/KSDS update was not performed. I was never notified of this update because Kia had an incorrect address on file for me. This failure is consistent with known Theta II connecting rod bearing defects that have resulted in recalls and warranty extensions. I believe this is a safety-related defect and am requesting review. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)
NHTSA complaint #11705206 — an unverified report by a vehicle owner.