What 1,000 owners told NHTSA about the 2015 Kia Optima

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 ODI 11745917

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 ODI 11745534

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 ODI 11742779

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 ODI 11742315

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 ODI 11740785

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 ODI 11738851

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 ODI 11736696

Engine seized while driving.

NHTSA ODI 11731047

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 ODI 11725883

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 ODI 11725022

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 ODI 11721582

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 ODI 11720091

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 ODI 11719695

Engine seized and won’t turn at all

NHTSA ODI 11719754

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 ODI 11717931

Valve cover leaking and oil dripping oil on exhaust at 114k miles. Risk of engine fire.

NHTSA ODI 11716870

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 ODI 11714265

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 ODI 11713208

Engine seized

NHTSA ODI 11709557

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 ODI 11705972

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 ODI 11705421

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 ODI 11705206

The contact owns a 2015 Kia Optima. The contact stated that while driving at an undisclosed speed, the engine seized. The contact stated that the check engine warning light was illuminated several minutes before the engine seized. The vehicle was towed to an independent mechanic, where it was diagnosed with engine failure. The contact was informed that the engine needed to be replaced. The vehicle was not repaired. The vehicle was then towed to the dealer where it was diagnosed with engine failure. The contact was informed that the engine needed to be replaced. The vehicle was not repaired. The contact was informed that the repair was not covered under warranty. The manufacturer was made aware of the failure but provided no assistance. The contact was informed that because the previous owner did not have an unknown software update performed, the repair was not covered under warranty. The failure mileage was approximately 138,000.

NHTSA ODI 11704313

The contact owns a 2015 Kia Optima. The contact stated that while driving at an undisclosed speed, the engine seized. The contact stated that the failure had occurred while driving on the highway. No warning lights were illuminated. The contact used a portable diagnostic machine but failed to retrieve a fault code. The vehicle was towed to an independent mechanic, where it was diagnosed with engine failure. The vehicle was not repaired. The contact was advised to tow the vehicle to the dealer. In addition, the contact was informed of an unknown recall for the year, make, and model vehicle. The vehicle was towed to the dealer, where it was diagnosed with engine failure. The contact was informed that the engine needed to be replaced. The vehicle was not repaired. In addition, the contact was informed of an unknown recall; however, the VIN was not under recall. The contact was advised to contact the NHTSA Hotline to report the failure. The manufacturer was made aware of the failure but provided no assistance. The contact was informed that the vehicle was purchased used. In addition, the contact was informed that the recall mileage limit was 100,000. The failure mileage was approximately 99,325.

NHTSA ODI 11704336

The incident took place on Sunday, December 30th. I was driving to pick up my children from their father and on our way home my car stopped accelerating entirely. This had only happen one other time a few days prior. I was in a gas station parking lot and initially when I turned my car on and went to put it into drive it wouldn’t accelerate. I thought that was odd so I did the only thing I knew how to, I checked my oil levels. Levels were full and no other issues were there. The check engine light had popped up when I turned my car back on but my car did accelerate so I thought nothing of it. I took my car to auto zone for a diagnostic and they told me my “B cam shaft” sensor needed to be moved and that could be causing the engine light to come on and ticking in my motor. I called a few shops getting quotes and eventually was forced to tow to the closest shop to me after my car refused to start overall. They replaced the battery and the b cam shaft censors and still were unable to get the car started. They told me 3 recalls were open on my car, including the motor and to have it towed to Kia for a full replacement. After calling Kia to have the repairs done, they refused me service based on a previous owner not handling prior recalls.

NHTSA ODI 11702641