Which parts fail
Components named in complaints (automatic and manual transmissions, CVT, axles, driveshaft, 4WD/AWD).
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 stated while driving at an undisclosed speed, the brakes and the steering column were inoperable. The contact stated that several unknown warning lights were illuminated. The contact was able to safely pull off to the shoulder of the roadway. The contact stated that the engine started smoking. The vehicle was towed to an independent mechanic. The vehicle was not repaired. The contact stated that in December 2020 and March 2023, recall repairs were completed on the ABS and TCU modules. The manufacturer was made aware of the failure, and a case was filed. The approximate failure mileage was 94,700.
The contact owns a 2015 Kia Optima. The contact stated that while driving at various speeds, or while at a complete stop, the vehicle would shut off without warning. The vehicle would resume normal operation upon restart of the engine. The vehicle was taken to a dealer for an inspection; however, the dealer was unable to duplicate the failure. The manufacturer was not notified of the failure. The vehicle was not repaired. The failure mileage was approximately 88,000.
The contact owns a 2015 Kia Optima. The contact stated while driving at an undisclosed speed, the vehicle lost motive power and stalled. There were no warning lights illuminated. The vehicle was towed to the residence and then to a local dealer where it was diagnosed with a wheel bearing failure. The vehicle was not repaired. The manufacturer was made aware of the failure; however, no assistance was provided. The failure mileage was approximately 120,000.
1.Since 1/17/23 I've had 5 occurrences of the car yanking me to the left as I am turning right. The steering wheel gets stiffed, the dashboard lights come one, car slows down and I have to park the car and turn it off and back on. When I turn it back on, no dashboard lights are on and the everything is back to normal as if nothing ever happened. I have taken the vehicle to the dealership 3 times for a diagnostics and nothing comes up. The vehicles computer is not even tracing the times the dashboard lights have turned on as it shows zero history and that is not the case. I have taken pictures and video of the dashboard lights and have showed the guys at the dealership but since there's no record on the dashboard computer/history, they're not able to determine the problem. 2.My safety has been put at risk as I can get involved in a car accident and involve others safety at risk as well. …
My 2015 Kia Optima EX with 56,462 miles which I am the original owner. On 09/07/2024, my vehicle oil light came on and the vehicle was taken to Weston Kia in Gresham, OR. This vehicle has had regular oil changes every 3,000 miles since purchased performed at Weston Kia. The service department found a leaking oil pressure switch and preformed the repairs totaling $248.60 on 09/08/2023. Per Kia 10yr/100,000 Powertrain warranty for original owner "In the Engine: Cylinder block, cylinder head and all INTERNAL PARTS, timing gear, seals and gaskets, valve cover, flywheel, OIL PUMP, water pump and turbo charger, pg. …
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. …
Vehicle experienced sudden loss of power while driving when cylinder 3 completely failed (0 PSI compression). Metal particles found in oil and excessive oil consumption (1 pint/100 miles). KIA dealer diagnosed as piston rings but ignored metal in oil that suggests bearing failure covered under recall campaign. Refused proper diagnostic testing. Vehicle now unsafe to drive with failed cylinder that could cause complete engine seizure while driving. Kia had all recommended services and oil changes since acquired in 11/2016. These service records demonstrate the progression of my vehicle's engine issues, from early oil consumption problems documented by York Auto Care in July 2023 (3 quarts low) to complete cylinder 3 failure with zero compression confirmed by Kia's own diagnostic testing in May 2025. …
While driving my 2015 Kia Optima (VIN: [redacted] ) at highway speed, the engine suddenly shut off without any warning lights, alerts, noises, or check-engine indicators. This created a dangerous situation for me and surrounding drivers. The vehicle had passed state inspection only 3 months earlier with no issues. The sudden shutdown is consistent with the known Theta II engine defect investigated by NHTSA. The car is now completely undrivable. Two Kia dealerships refused to assist, claiming that they cannot perform KSDS because the engine is already dead. These reasons directly contradict the Kia Theta II engine settlement terms. This sudden stall is a safety hazard and could have caused a severe crash. I am requesting that NHTSA review this incident as a potential recurrence of the engine-stall defect already documented in Hyundai/Kia vehicles.
For one my car is very sluggish when taking off and shifting gears Jerks badly. MY electrical is messing up on my radio and camera. Sometimes I smell rubber burning. When I have my cruise on it will speed up on its on and jerk when it does and when i press my brakesbto slow down it doesn'twant to slow down unless iash really hard. When taking off from a hill or a dead stop it doesn't want to shift and slags and rattles when it shifts. Bluetooth works sometimes and sometimes it doest it depends on when my backup camera works or not. I bought this car used in June of 2021 with a little over 92000 miles. I know when something doesn't sound right and when something is messed up, there is something wrong with my car. So far I haven't been in an accident but I don't want to be either.
My 2015 Kia Optima Hybrid poses a serious safety risk. While driving at highway speeds, the car has randomly shut off multiple times. A "Check Hybrid System" or hybrid battery warning appears on the dashboard, and the vehicle either loses power entirely or switches to electric-only mode and coasts to a stop. This happens without warning, putting my life and the lives of others at risk. I already had the relevant hybrid system recall work completed by a Kia dealer, but the issue persists and the car remains unreliable and unsafe. This appears to be a known issue affecting many 2011-2016 Optima Hybrid vehicles. Kia needs to be held accountable for continuing hybrid system failures that occur post-recall and outside of warranty. This is a dangerous, recurring defect.
Transmission complaints in other Optima years
Frequently asked questions
How common are transmission problems on the 2015 Kia Optima?
NHTSA has 49 complaints about the transmission & drivetrain of the 2015 Kia Optima, 5% of the model year's 1,009 complaints. The component named most often is automatic transmission › internal › bearings/bushings (1 mentions).
Is there a recall for 2015 Kia Optima transmission problems?
No. NHTSA lists no transmission & drivetrain recall for the 2015 Kia Optima, though it has 4 recalls for other components. If the problem is widespread, a repair may still be covered by an extended warranty or a manufacturer service bulletin — ask a dealer.
At what mileage do 2015 Kia Optima transmission problems start?
Half of the complaints with a recorded mileage happened before about 83,000 miles, and 10% before 25,000 miles.
Is it dangerous?
Owners linked 1 crash, 1 fire and 0 injuries to transmission & drivetrain 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.