general problems of the 2015 Kia Motor Optima - part 1

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.

While driving my 2015 kia Optima (VIN: [xxx] ) 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. Information redacted pursuant to the freedom of information act (foia), 5 u. S. C. 552(b)(6).

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. Despite this documented history and kia's own test results showing catastrophic engine failure, they have denied warranty coverage under their engine campaign that specifically covers bearing-related failures on my 2015 kia Optima 2. 4l.

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.

Was driving down the highway and all of a sudden the car shut down in the highway lucky cars was not close by. Tried to crank it it would not crank would not take a boost it won’t say anything I had the battery checked at auto zone the battery is really good. The mileage on the kia Optima is 1,900 actual miles it will not crank or move it was very scary I called kia customer service there wanted to charge me over $400. 00 dollars to come get it and take it to the shop so it took me 2 days to find a tow to get it home and it still needs to go to the kia shop.

Engine locked in while driving on road no power an won’t start.

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.

I need remedy compensation in regards of my recalls my engine warranty was gone after being replaced due to engine seized 01/01/2023 I had engine warranty since 2020 and now my car was being rejected refused rejected excluded iam being discredited I own my 2015 kia Optima I lived sleep in my car iam hoing through financial hardship since 2021 I need legal advice help assistance please.

The vehicle has a seized motor within the manufacturers powertrain warranty. They are denying to repair/ replace the motor because they claim a recall was not performed. The NHTSA does not currently show the recall that needed to be performed. The vehicle should still be covered by kia's powertrain warranty and the dealer is not accepting responsibility.

My car is dragging/hesitant to pick up speed. While on the highway, it takes a while to reach minimal speed. No warning lights are on, but one mechanic advised code, under turbo boost. My steering wheel vibrates at speeds above 40 mph (unsure if it's related to turbo), but no one seems to be able to find the core of the problem for repair, kia dealership included. I've been trying to seek repair for close to a year, without satisfaction.

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. 6. " I believe this part is covered per kia warranty and the definition of drivetrain "a powertrain is a system inside a vehicle, in a car, a powertrain consists of the engine or motor and its internal components, such as the energy storage system, transmission and driveshaft. " after reviewing all kia warranty information and speaking to customer service at 800-333-4542 (who stated the repairs are not covered), there is no information to the contrary that a oil leaking pressure switch that is located within the engine block is not covered. Kia would not provide any detailed information that shows this part falls outside of the terms of my 10yr/100,000 mile warranty.

The contact owns a 2015 kia Optima. The contact stated that while driving at an undisclosed speed, the brake and steering column were inoperable. The contact stated that all of the warning lights were illuminated. The contact stated that she was able to safely get the vehicle to the shoulder of the road. The contact stated that the engine started smoking. The vehicle was towed to an independent mechanic shop. The vehicle was not repaired. The contact stated that in December 2020 and March 2023, recall repairs were completed for 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.

Driving on highway at 65 mph and engine just died with no warning. Almost got hit trying to get off the expressway to the side of road. Had car towed home and checked engine. Engine is seized up completely.

Was driving down the interstate and engine cut off suddenly. Had to coast across several lane to pull over out of traffic. This was very dangerous. Had car towed home. Engine is locked up . Called kia dealerships near me. Closest one is not accepting any engine replacement appointments at this time and don’t know when they can. Wouldn’t even give me a future appointment. Kia lawsuit website says my VIN number is covered for engine replacement but I can’t get a dealer to even look at it.

Knock sensor replaced due to engine knocking did not fix the problem the cars engine does not work it julks and pulls really hard engine noise check engine flashing left me stalled on the main highway with my 2 children with no warning the car has engine oil to adequate levels maintenance was up to date.

The engine lost power taking off crossing a major roadway, resulting in a stall, vehicle had to be restarted in a panic. The knocking and loss of power put me and my passenger in danger of a side impact from cross traffic. The issue was reproduced by a dealer upon further inspection. The vehicle will be inspected by a service department at certified dealership. No warnings lights or fault warnings appeared related to this issue.

On 3/1/23 on my way home from my which the site was in perth amboy, NJ. At the north somerset rest stop, just exited the I-76 westbound. I lost power around 65 mph. I didn't get any response from my brakes at first and nothing from my accelerator. Upon drifting and praying that I'd make it to the lot out of the main exiting lane. Upon pulling into a spot at the very farthest spot from the building, I noticed my check engine light is flashing. Press my brakes were working. Accelerator was hardly responding. I've worked on my car and my families cars, and cars most of my life. I had my code reader with me. Plugged it in and got the code that I've heard and read about. P1326 knock sensor. Knowing about this about kia and hyuandi, I knew my engine was dead. Thank god it didn't catch fire like some others have. I had it towed to smail kia in greensburg, PA. That was the closest and not the dealer I bought it from. We bought it from century 3 kia west mifflin, PA. After their promises that the engine would get replaced, lack of communication, many of my calls,voicemail, emails and showing up in person,(had to move 2 things that would've been in the way of the swapping of the engine) and a week later kia denied my replacement due to "power adders". None of which I have, use or cause any issues. No testing was done on what they thought was power adders. However, all of the tests that show their faulty engine components as perr the federal lawsuits and recalls. . . . . All failed! I can't drive the car. It's dangerous for myself and any other motorist. Could explode, catch fire or completely fail on any highway/roadway. I need my car for my career and above all, my life sustaining health and medical appointments now I'm left with no vehicle. I still owe around a year- year and a half. As well as car insurance. Now what? kia needs to do the right thing here, for myself and anyon else suffering from this horrific life changing nightmare.

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. The vehicle doesn't give any prior signs when it's going to act up when turning to the right, therefore it can happen at any given time. The first time I was leaving a parking lot and it happened on the freeway feeder. I towed my vehicle to the dealership the first time as I was in fear of driving it only to be told they can't find the issue. 3. The dealership has ran 3 different diagnostics on 3 different occasions and nothing comes up. It is still unresolved. 4. Kia service department has inspected in on 3 different occasions since the first incident. 5. No warning lamps or warnings of any sort before the first incident.

1. While stepping on the brakes my car has revved up as if I was pressing the gas. So I let my foot off the pedal and pressed the brakes again. This happened 2 times that week. And another time while I was coming to a stop light as I pressed the brakes, my car revved up but didn’t actually make my car speed up. I had to press the brakes again for it to stop. 2. My battery was smoking and I replaced it. 3. My car is consuming oil. The dealership did a series of oil consumption testing due to the exhaust leaving extra carbon residue on my car. They said it was fine but I don’t think they solved the issue.

August 6, 2022 on kansas turnpike near el dorado. 2015 kia Optima lx 74,000 miles. With absolutely no warning whatsoever revved high then began a knocking sound, then a horrible banging and died. No lights, no alarms. Steering became a problem. We were able to drift to the side of the road as we were already in the right lane. Once completely stopped dash lights came on. We had no idea of any recalls or issues. Engine never recovered and we procured roadside assistance. Waited 4 hours on the side of the turnpike. We have since learned of a class action lawsuit against kia with this very issue. We are still waiting for an engine replacement/rebuild 15 weeks later!.

Unknown but I got my car in February, it’s always been sounding rough from the start but was told it’s normal, lately the past few months I noticed a little vibration and a change of sound in the motor but had no lights come up on dashboard so assumed it wasn’t a problem. Well to this day my engine is shaking very rough that my car vibrates extremely and making a clicking sound best way to describe it and my engine light as well as oil topper light came on just a few days ago which I’ve gotta an oil change roughly about 2 months ago and added oil as well recently. So not sure if I have a leak of some sort or what. My breaks are also bad but when I purchased the car one tire was missing two bolts cause they broke off. Lately a lot of problems have all come at once. But I don’t feel safe driving my car cause I feel it doesn’t accelerate as it should and it’s not running normally. It’s a 2015 kia Optima. Says no safety recall but all the problems I’ve been having seem very relatable to what’s showing on the recall list for kias of my year.

2015 kia Optima hybrid hev system. Months after purchasing the vehicle two different lights would come on the engine. One is the hev warning light and the other is a flashing “turn off engine and check hev system”. The first time it happened the vehicle turned off. It was towed to kia, 02/2020. They change some sensor and sent me on my way. 3 weeks later the hev warning light came on again so it was towed to kia for the 2nd time, 03/2020. This time they said they could not recreate the issue. A month later the light came on again and again but since the light never stayed on, I kept getting told by kia that I’d have to take it in when the light stayed on. 01/2021 the light came on again, with the flashing warning and the vehicle turned off, mid-drive. It was towed to a mechanic shop near me, where they replaced the wiring harness completely, but a month later the same light came on again. Over the course of the year, the warnings kept turning up and time and time I kept getting told they needed the light on at the dealer so they could determine with the codes, what is wrong. 07/2022, light came on as I was merging on to the freeway and the car shut off. I was able to make it turn on and make it home safe. The next day I towed it to the shop where they replaced the wiring harness and they stated they could not touch it further since the codes they got where “high voltage battery” codes and a specific tech is the only one when could work on it. I took it to kia where it stayed 33 days. They changed a part. Two days later the hev light came on again, so I took it back. They kept it one day, drove it 60 miles and they could not recreate the issue. I got it back on Saturday, 5 miles out the light came back again and again. I took video. Called kia and now the car is back at the dealer while they try and figure out the issue. I’m scared for my life. The car gives no warning when it decides to shut off. Wheel locks on the times it does turn off. Hev system is no good.

In 2020 a message saying “check hybrid system, stop vehicle and turn off engine appeared and the car stopped while I was driving. I brought it to the kia dealership and they “fixed the problem”. On Tuesday may 31st I was driving home on the expressway and my car stopped. I luckily was able to pull off to the side and then the same message popped up and the car would not drive anymore. I have had 5 recalls with this car and it is only 7 years old.

Engine/motor failed which disabled the car on highway. Traveling on 3/4 lane highway with heavy traffic. Safety was risked due to almost being hit from behind and cars swerving out the way. Problem was assessed and thought to be repaired but occurred again causing more possible damage to engine. Warning lamp illuminated seconds before the car shut off which was not enough time to pull over safely. Car had to be towed off highway.

1. The O2 sensor malfunctioned causing check engine light to come on. The catalytic converter failed or malfunctioned, an it is available for inspection upon request. 1wk after replacement of O2 sensor installment, check engine light illuminated once again. [official diagnosis was the catalytic converter was faulty but no mention of replacing 02 once catalytic converter was fixed]. 2. My safety as well as my children's safety was put at risk because there was and still is (even after repairs made from dealership where car was purchased) an issue with broken exhaust system and leak. A broken exhaust system poses extreme danger because it releases carbon monoxide (CO)- an odorless ,tasteless, highly toxic gas, which can travel in passenger area and cause carbon monoxide poisoning. Overexposure to this odorless and colorless gas can cause death. Even in mild cases of exposure to CO can cause headaches, dizziness, nausea and fatigue. I need not mention that the extreme or excessive temperatures caused severe discoloration where the three- way catalyst is located. The pistons could have melted as well could have caught the car on fire . My safety as well as every occupant that ever traveled in the vehicle thus far, was at risk. The exhaust leak was big enough to affect the oxygen levels, to spring that code. Another safety risk was when owner of car was falling asleep at wheel of car while driving, not knowing there's a leak. This put the owner and the vehicles occupants at risk which is the greatest threat by far. 3. The problem has been confirmed by rivard Buick GMC. 4. The vehicle has not been physically inspected by the manufacturer or police but has been insoected by insurance representatives. Yes there warning lampsthat appeared as the check engine light came on each time the exhaust system was malfunctioning. There was/ are other symptoms prior to the failure 1st appeared 11/01/21 O2 sensor, 11/15/21 catalytic converter, 01/28/21 symptoms wo.

Driving one day in Dec 2021, and there was a hybrid system warning and vehicle suddenly stopped on the road. Called tow truck. We were unable to put the car in neutral to tow. Had tow truck deliver to dealership for diagnostic and repair. Dealer replaced transmission and stated it was covered under warranty. Finally got vehicle back and warning still pops on dashboard. We’ve taken it back several times and warning randomly appears. Dealership unable to recreate the warning to diagnose. Unable to drive the vehicle over long distances due to safety concerns.

I have 2015 kia Optima grey or platinum graphite exterior color since Aug 2019 I had an tbone accident last Dec 26 2021 which iam not at fault for never received any type of comfort care claim it was during covid pandemic I was in the process of grieviance being hate left in despair also job loss with no income unstable living situation which I was living on my personal vehicle been going through financial hardship until present I havent been driven until I brought to kia dealership Jan 1st of 2023 due to my personal injury and car accident it was left parked got towed with busted windows had my personal belongings being gone missing. . . . I have rough years. . . It was difficult for me to get back up in my feet my car has recalls arent being repaired fairly. This will be my first time to adhere my concerns I would like to get some assistance if possible. . . I thank you in advance.

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.

Driving north bound on the 405 at freeway speeds, the vehicle showed several warning lights on the dash. Check engine light, oil light and 2 others, the vehicle lost engine power and only had brakes. I was able to shuffle off the main freeway to an off ramp where I pulled over to attempt to power the car back on. The smell of electrical fire started to become apparent and I went out to lift the hood and smoke began to come out the opening. I rushed to get my kids out the vehicle and attempted to pull the battery cable off to try to salvage it from catching fire. I was able to wiggle the battery cable off but smoke continued to come out. The vehicle was eventually dropped off at the dealership car pros kia in glendale and im being informed the starter was the issue and will need to be replaced. Im uncertain about the diagnosis since the event of the vehicle losing all power occurred during highway driving .

Vehicle had service light on for engine. I took it to the dealership and they said it's ok to drive today until they service in the morning. They had a sensor show for the heuc. I drove 10 miles approximately half on freeway and at full 65mph the car made a very loud electrical noise and lost full drive power. I was able to safely avoid getting hit at full freeway speeds in rush hour and able to get on shoulder and exit ramp. Car turned back on and would not exceed 15mph at the light and was towed today directly to the dealership for further inquiry.

Engine seized while driving and wouldnt start. I bought a new battery and tried to start it and it almost caught on fire. I had it towed to a kia dealer and they replaced the engine and the turbo system which had a recall on it in 2016that was for the knock sensorsystem on 2018/.

I was driving on interstate 40 in tennessee and my car just stopped running. I was in right lane and I pulled off to shoulder. A dot emergency repair truck stopped and tried to jump my car, but nothing happened, not even a noise or anything. Called aaa for a tow.

P1236 knock sensor code. Car went into "limp home mode" while driving down the freeway at 55 mph.

My 16 year old son saved his money (since 13 years old) and purchased back in October 2019 the car used from a dealer with 79546 miles on the car. On February 18, 2020 on his drive home from school he noticed a loud knocking noise. He was not sure where it was coming from, no warning lights came on whatsoever. He drove the car straight home. My husband checked the oil and the dip stick had no oil on it. The car at this time only had 82794, it's last oil change back when we purchased it in October at 79546 miles. How does a car burn through synthetic oil in a little over 3k miles and 5 months of driving. We had the car towed to an independent auto repair shop which stated the engine failed and needed to be replaced due to bearing failure. After doing a lot of research online, it appears there is a pending class action lawsuit with Hyundai and kia but it appears the hearing for preliminary approval of the proposed settlement has not been released. I wish as a parent we would have done our due diligence of researching about the reliability and safety of kia vehicles because knowing what I know now, I would have never allowed this purchase. I feel completely screwed and now my poor 16 year old has no car because he doesn't have 6k to fix it. What a terrible first car purchasing experience for my son. Please get kia corporation to due the right thing and get these cars off the road. They need to go back to the drawing board in regards to the design of their engine.

My vehicle is among the vehicles registered/qualifying for a recall. My dealer was to have replaced my entire engine during the first recall my vehicle received. Within a week/some 5 days or so my check engine light was back on. Taking the car back to my dealer, it was suggested that I pay $145 just for them to do a diagnostic on the/my vehicle they had just serviced. My car is currently registered/qualifies for a recall that stems and or is related to the previous recall that my car had. . . As recently as a few days ago (1/8/2020), the same dealer supposedly �fixed� the recent recall. I'd went by the dealership, they serviced the vehicle - check engine light went/was off. I'd say what was an hour or so having the car back in my possession from the dealer, the check engine light was back on. I'm appalled at the fact that I'm currently experiencing a issue that has been on going over a year. In my research on recalls I'm not to be charged anything by law surrounding rectifying a recall. On more than one occasion my dealer has suggested that I pay after feeling that they've rectified the problem concerning my vehicles recall. I have valid third party diagnostics that interestingly enough were free, unlike the diagnostics my dealer would suggest I pay for on a car that is surrounded by a serious recall issue. And more interesting is my having received a diagnostic that rendered the results that are the same codes surrounding the recall, and this after/on a day/ the last day - my car was serviced/supposedly �fixed. � I'm appalled at the suggestion that I �upgrade,� into a new car, pay anything, how any car having received a �new engine,� though 5 days later the check engine light is back on - that's �scary. � I have necessary documentation that can show my dealer is oblivious to public safety laws surrounding recalls due to remedies they suggested on �fixing,� my vehicle.