Which parts fail
Components named in complaints (engine, cooling system, oil leaks, timing chain, exhaust).
Mileage when the problem started
Owner reports
Selected complaints filed with NHTSA by 2015 Kia Optima owners, lightly cleaned up (personal details are redacted by NHTSA).
The contact owns a 2015 Kia Optima. The contact's daughter was driving at approximately 60 MPH when numerous lights on the dashboard illuminated. The contact stated that her daughter said that the vehicle stalled, however, she was in the right-hand lane and pulled over. The daughter said that smoke was being emitted from the engine compartment. The contact stated her daughter was picked up by family and the vehicle was left at the side of the highway. The contact stated that the daughter's companion retrieved the vehicle. The contact stated that he opened the hood and checked the oil and observed that there was no oil showing on the dipstick. The contact filled the vehicle's oil reservoir and started the vehicle. The contact said that he also reported that all panel warnings illuminated and the vehicle had begun to emit smoke. …
The contact owns a 2015 Kia Optima. The contact stated while the daughter was driving at approximately 80 MPH and attempting to pass a tractor-trailer in the left lane, the vehicle behind her aggressively merged into the same lane causing a crash to the passenger side of the vehicle. The other vehicle fled the scene. The contact's daughter merged to the shoulder of the road. There was damage to the front passenger side door, and front passenger wheel well, and tire. The vehicle failed to restart. The police were on the scene however no Police Report was filed. There were no injuries reported. The vehicle was towed to a collision center for cosmetic repairs but the vehicle failed to start. The vehicle was then towed to a local dealer. The dealer diagnosed that the engine had failed and needed to be replaced. …
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 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 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 contact owns a 2015 Kia Optima. The contact stated while driving at 15-20 MPH, the vehicle inadvertently stalled and she saw smoke coming out from underneath of the hood of the vehicle. There were no warning lights illuminated. The contact stated she was able to exit the vehicle. The vehicle was towed to the contact's residence, then it was towed to the dealer who diagnosed that the engine had ceased. The dealer informed the contact that she would be responsible for the cost of the repair. The vehicle was towed to a second dealer (Kia of Riverdale 1 Windbeam Rd, Riverdale, NJ 07457). The manufacturer was notified of the failure and did not provide any assistance due to the fact that the previous owner of the vehicle had not completed the software update of the vehicle. The contact stated the failure was related to NHTSA Campaign Number: 21V331000 (SERVICE BRAKES, HYDRAULIC). …
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 contact owns a 2015 Kia Optima. The contact stated that while driving at 25-30 MPH on a one-lane road, the vehicle inadvertently began to stall. There were no warning lights illuminated. The contact stopped and turned off the vehicle but was unable to restart the vehicle. The contact attempted to jump-start the vehicle with the assistance of her friend however, the vehicle failed to start. The contact's friend informed her that he smelled a burning odor. The vehicle was towed to the contact's residence. The vehicle was then towed to an independent mechanic who diagnosed that the battery, the starter, and the engine had failed and needed to be replaced. The dealer was notified of the failure and advised the contact to bring the vehicle to their location for diagnosis. The manufacturer was not notified of the failure. The vehicle was not repaired. …
The contact owns a 2015 Kia Optima. The contact was made aware of NHTSA Campaign Number: 21V331000 (Service Brakes, Hydraulic) on Facebook. The contact called the local dealer and made an appointment for March 25, 2023. The contact stated on March 23, 2023, while driving 50 mph, depressing the accelerator pedal but the vehicle began to decelerate. The contact stated the battery warning light was illuminated. The contact was able to park on the side of the road and when exiting the vehicle she saw smoke but no fire/flames exiting the hood. The vehicle was not drivable. The contact towed the vehicle to her residence. The contact called the local dealer and made them aware of the failure. The vehicle was not diagnosed or repaired. The manufacturer had not been informed of the failure. The failure mileage was approximately 180,000.
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.
Related recalls
Engine
Kia Motors America (Kia) is recalling certain 2011-2017 Optima, 2012-2017 Sorento and 2011-2018 Sportage vehicles that previously received an engine replacement under recall number 17V-224, warranty, or the Knock Sensor Detection System (KSDS) Product Improvement Campaign.
Remedy: Kia has notified owners, and dealers will inspect and replace the fuel pipe, as necessary, free of charge. The recall began January 17, 2019. Owners may contact Kia customer service at 1-800-333-4542.
NHTSA investigations
Loss of Motive Power
The National Highway Traffic Safety Administration (NHTSA) received a letter dated July 13, 2022, petitioning the Agency to initiate a safety defect investigation into loss of motive power allegations attributed to oil drain pan assembly failures on certain Hyundai Motor America, Inc. and Kia America, Inc. vehicles spanning Model Years (MY) 2005-2021.
Engine complaints in other Optima years
Frequently asked questions
How common are engine problems on the 2015 Kia Optima?
NHTSA has 647 complaints about the engine & cooling of the 2015 Kia Optima, 64% of the model year's 1,009 complaints. The component named most often is exhaust system › manifold/header/muffler/tail pipe (1 mentions).
Is there a recall for 2015 Kia Optima engine problems?
Yes — NHTSA recall 18V-907 (engine, Dec 19, 2018). Recall repairs are free at authorized dealers.
At what mileage do 2015 Kia Optima engine problems start?
Half of the complaints with a recorded mileage happened before about 88,000 miles, and 6% before 25,000 miles.
Is it dangerous?
Owners linked 11 crashes, 52 fires and 9 injuries to engine & cooling problems on this model year. If you notice symptoms, have the car checked before driving further.
Source: U.S. National Highway Traffic Safety Administration (NHTSA) — owner complaints through October 20, 2026, recalls and defect investigations; fuel economy from the EPA. Complaints are unverified reports and are not proof of a defect. How we rate model years.