2018 KIA Optima engine problems

ENGINE

The contact owns a 2018 Kia Optima. The contact stated that while driving at an undisclosed speed, the vehicle failed to accelerate and failed to exceed 52 MPH. The vehicle shut off. The contact stated that the engine was running rough while stationary and the vehicle shut off without warning. The vehicle was taken to an Auto Parts Store, where it was diagnosed, and it was determined that the vehicle was in LIMP Mode with knock sensor codes displayed. The vehicle was not repaired. The manufacturer was notified of the failure. The failure mileage was approximately 136,000.

NHTSA complaint #11758363 — an unverified report by a vehicle owner.

ENGINE AND ENGINE COOLING

See attached document for complaint.

NHTSA complaint #11752131 — an unverified report by a vehicle owner.

ENGINE

I’ve had my 2018 kia optima for round about two years.I only got this car because they refused to replace my previous engine on my 2015 Kia optima,even though I had a warranty but that’s another story(Kia on the Blvd).This car have given me problems from the start.Going through oil in less than a month,which they can never find a leak,not being able to go over a certain speed before I start to hear noises.Ive complained about noises,they act like they can’t hear,and said nothing is wrong with the engine when previously checked.My check engine light has came on twice and both times the car was malfunctioning on the highway resulting in me have to get a tow.First it was plugs replacement now I need a whole new engine.I really don’t know what to do at this point.I believe they sold me a faulty car

NHTSA complaint #11749282 — an unverified report by a vehicle owner.

ENGINE

The car burns oil within a week of getting an oil change. It was only driven a 200 miles before all of the oil was burned out. This has been a consistent issue with this car that the oil burns at an extreme rate. This is a safety risk as it could lead to engine overheating, the engine could stall out due to the fast burning of the oil, or a potential fire hazard while driving. The oil light will come on for a second and at that point, the oil is already EXTREMELY too low. I brought the car to the mechanic and they have told me multiple times that there is no leak or anything. The mechanic says that the car simply is burning oil too fast.

NHTSA complaint #11746528 — an unverified report by a vehicle owner.

ENGINE AND ENGINE COOLING:ENGINE:ENGINE CONTROL MODULE (ECU/ECM)

The contact owns a 2018 Kia Optima. The contact stated that while driving at an undisclosed speed, there was an abnormal odor and a knocking sound coming from the engine. The vehicle was taken to the dealer; however, the dealer was unable to duplicate the issue. The vehicle was not repaired. The issue persisted. The contact stated that the vehicle was later returned to the dealer to be repaired under a service campaign involving the engine control unit (ECU). Shortly after the vehicle was repaired, the ECU failure message was displayed. The vehicle subsequently became inoperable. The vehicle was not repaired. The manufacturer was notified of the issue. The approximate failure mileage was 1,500.

NHTSA complaint #11745997 — an unverified report by a vehicle owner.

ENGINE AND ENGINE COOLING

The contact owns a 2018 Kia Optima. The contact stated that while attempting to accelerate from a standing start the vehicle had experience sever jerking and hesitation. Also, the vehicle has experience oil consumption problems and the contact constantly added engine oil. The cause of the failures were not determine. Also, the hood latch had malfunctioned and the hood could not opened to add oil to the engine. The cause of the failures were not determined. The local dealer and manufacturer were notified of the failures but no assistance was offered. The failure mileage was 121,000.

NHTSA complaint #11736008 — an unverified report by a vehicle owner.

ENGINE

2018 Kia Optima LX, 2.4L GDI Theta II engine. Approximately 128,000 miles. Reporting severe internal oil consumption that has progressed to engine misfire and shaking, consistent with late-stage Theta II connecting rod bearing failure. The vehicle is now unsafe to drive and has been parked. Timeline: Purchased as a Certified Pre-Owned vehicle in December 2021. Excessive oil consumption began shortly after purchase. For approximately 4.5 years I have added about 1 quart of oil every 2 weeks to keep the engine from running dry. No external leaks have ever been found by any mechanic. Multiple independent mechanics attempted diagnosis and repair over this period. None resolved the issue. The vehicle has now developed a pronounced shake and apparent engine misfire, the textbook progression to rod bearing failure documented in NHTSA investigation PE19-004 and prior recalls/campaigns 17V-224, SC147, and SC172. Safety concerns: Sudden engine seizure or stall at highway speed creates a serious crash risk for me and surrounding traffic. Theta II 2.4L GDI rod bearing failure has been associated with under-hood fires. The defect develops gradually with no warning to the driver beyond elevated oil consumption, which is frequently dismissed as normal until catastrophic failure occurs. I am filing this complaint to document the failure and to add to NHTSA's data on the Theta II GDI 2.4L engine in 2018–2019 Optimas. This model year was excluded from the original 2017 recall but is included in the Hyundai and Kia Engine Litigation class settlement and the lifetime engine warranty extension. My vehicle's symptoms match the defect pattern exactly. I will pursue warranty engine replacement, but I want this safety failure on the federal record regardless of how Kia responds.

NHTSA complaint #11734333 — an unverified report by a vehicle owner.

ENGINE

Consuming fuel to the amount of roughly 1/2 quart per 150 miles. Vehicle has been inspected by mechanic and the oil pan, oil filter, and PCV valve has been replaced and engine oil UV dye added and cycled with no leaks found. The risk is that if not rigorously checked often, the engine will malfunction because the car runs out of oil. I have had my mechanic checking this car since I purchased it in January 2026. We have had to replace the oil pan and do two full oil changes with three separate quarts of oil being added in between all of that to keep it topped up. My mechanic agrees that the engine is consuming oil at an extremely high rate. My mechanic and a mechanic at the dealership where I purchased it are the only one who has inspected the car for this issue so far. The mechanic at the dealership is who recommended we replace the oil pan to see if that fixed the leak, which my personal mechanic did. Yes the critical engine failure lamp illuminates on the dashboard when the oil ran out the first time while I was driving it. This was how I discovered that there was an oil leak. This specific incident occurred three weeks after I purchased the car which I bought in mid-January of 2026.

NHTSA complaint #11731478 — an unverified report by a vehicle owner.

ENGINE

My teenage daughter regularly drives this vehicle. The vehicle began experiencing significant oil consumption, oil leaks, and intermittent loss of power. During an early inspection at an independent repair facility, a check engine code P1326 was identified. Due to the symptoms and diagnostic code, the repair facility advised that the vehicle could be heading toward engine failure and recommended that the vehicle be taken to an authorized dealership because potential engine issues may fall under manufacturer warranty coverage. The vehicle was then towed to an authorized dealership. During the first visit, the dealership retained the vehicle for an extended period of time, approximately two months. During that visit, several recommended services were completed, including replacement of spark plugs, ignition wires, and replacement of the valve cover gasket along with other recommended maintenance. During that visit, it was also stated that the vehicle has a known issue with excessive oil consumption. Because of this, the oil level is checked weekly and oil is added as needed. I also informed the dealership that the independent repair facility had identified code P1326, but I was told that the dealership diagnostic codes were different. After these repairs, the vehicle experienced another incident where it lost power and began idling roughly while being driven on a busy highway. The vehicle was taken back to the dealership. During that visit, it was stated that the fuel injector harness and oil pressure sensor needed to be replaced. The dealership also indicated that the spark plugs needed to be replaced again, even though they had been replaced at the same dealership less than a year earlier. At that time, I asked if the vehicle would be safe to drive for approximately one week because I needed to travel out of town and my daughter would need the vehicle. The dealership advised that it was safe to drive during that time. The vehicle was then brought back to the deal

NHTSA complaint #11723632 — an unverified report by a vehicle owner.

ENGINE

It started with the oil. I constantly have to add oil. when it first started that’s what I was doing just adding oil. Then it got worse the engine light started to come on and it no longer gives me the low oil warning. I took it to the dealership and it was there for about three weeks. They said that the car needed a system update, they updated it and i took it home after that. Its been about a year since then and my car is still having the same issue and getting worse. I had to change the spark plugs a few times since then i also have oil coming out the back pipe and it’s been doing this since before I took it to the dealership. I also had to spend money on a rental car while it was at the dealership.

NHTSA complaint #11710029 — an unverified report by a vehicle owner.

ENGINE

I turned the car off, it had difficulty turning back on and the brake pedal got really hard. I had to wait about 30-45 minutes and then I was able to get the car started and brake pedal back to normal and no lights. Recently, I left the car on to run into a shop real quick and come back out. When I got back to the car, the power steering light, battery, and warning light?(amber triangle with ! In the center of it) were all on. I rev the engine and the issue went away for a quick second but then came back on. To avoid turning my car off and being stuck, I just shift to reverse and tried to leave. I’m backing out of the spot and now the backup camera is going in and out lights flashing on the dash and I’m trying to brake but the brake pedal isn’t registering and next thing you know, I’ve backed into a guard rail. On the way to drop my kids off at the babysitter, I was coming to a stop sign, and my car wouldn’t brake, i went through oncoming trafic and had to run off the road. KIA did a multi point inspection a few months apart from one another. One the car tested fine, then the second time they are saying a brake booster and no engine oil in the vehicle and that the car is basically trash. The oil light goes on and off and I can smell burning oil. I still owe 7 grand on this car and I just bought it last year and it was seamingly fine.

NHTSA complaint #11709575 — an unverified report by a vehicle owner.

ENGINE

I was sold an unsafe vehicle at J and J Auto house 6446 Wilshire Bl LA,CA 90022. Dealer withheld condition of car . Had car three months and was stranded on highway. Car was towed to Kia dealer and diagnosed with complete engine failure. Dealer will not honor limited warranty, shady sales practices withheld recall info during sale, won’t allow his mechanic to look at car, dodged calls, denied request to return car for refund

NHTSA complaint #11709524 — an unverified report by a vehicle owner.

ENGINE

My engine is under the Kia class action lawsuit for the KDS with the rod bearing clearance issues. I have done all my oil changes with paper work available. I got the update to the ECU several years ago as needed to be covered. Now my engine has failed and I took to the dealer to check but they said I didn't have a specific code and that they can't do any testing to verify it would be under the warranty. I called Kia Customer Care and have talked to them several times. They have told me there wasn't a need for the code and that the dealer could do other testing. The dealer stated that they can't do the BCT test due to a cylinder not having compression. I told Kia this is all related to the bearing going out and they said they can't do anything if the dealer said it's not under warranty. So I have now been going in circles with kia and dealer since 11/18/25. I sent kia another email on 12/15/25 and another on 12/18/25 due to not receiving a response. It's now 12/23/25 and still no response. They have a service bulletin that I seen online that was for dealers if any issues with testing they had other options but still nothing has been done.

NHTSA complaint #11706817 — an unverified report by a vehicle owner.

ENGINE

While driving my 2018 Kia Optima S, the car suddenly jerked, lost power, and stalled in traffic. Multiple warning lights came on at the same time including the oil light, battery light, and check engine light. I had no acceleration and the brakes became very hard to press. The vehicle had to be towed for safety reasons. The Kia dealership inspected the vehicle and confirmed internal engine failure due to “cylinder failure” and stated the engine needs complete replacement. This failure occurred without any external leaks and without warning other than the sudden loss of power. The dealer stated the issue is not covered, even though it is clearly an internal engine malfunction. This is a major safety hazard because the stall happened while I was in active traffic. A sudden loss of power and braking ability puts me and others at risk of an accident. The problem has been confirmed by the Kia dealership through diagnostic testing. The vehicle is still available for inspection. Warning lamps appeared only at the moment of failure, giving no advance warning. This appears to be related to the ongoing engine defects in Kia vehicles involving oil starvation, loss of compression, cylinder scoring, and internal engine failure. Cylinder failure and sudden stalling should be investigated as part of the known safety-related engine defects affecting this model.

NHTSA complaint #11704303 — an unverified report by a vehicle owner.

ENGINE

Car keeps stalling while driving

NHTSA complaint #11701737 — an unverified report by a vehicle owner.

ENGINE

On August 26, 2025, I brought my 2018 Kia Optima Plug-In Hybrid to an authorized dealer for recall SC218 (engine inspection and KSDS software update). The dealer verbally stated both SC218 and SC278 recalls were completed, and the repair order (RO #XXX) lists them as performed. In September 2025, Kia America emailed me showing recall SC218 still open, and a warranty coverage report dated September 26, 2025, again listed SC218 as unclosed. On November 4, 2025, NHTSA’s official VIN lookup confirmed the recall remains “Incomplete.” On October 21, 2025, Kia America emailed me under Case #XXX stating that SC218 was “confirmed completed” and that the dealer performed a software update to the ECU, referencing RO #XXX. However, NHTSA’s database still lists recall SC218 as incomplete. This contradiction between Kia America’s internal record, the dealer’s invoice, and the federal NHTSA database raises a serious safety concern that the recall inspection or software update was never actually performed or was never reported correctly. I have requested written proof and diagnostic data (Battery SOH report) multiple times but have not received them. If accurate, this means I was led to believe my vehicle’s engine-safety recall had been repaired when federal records still list it as open. I am requesting NHTSA to review this reporting discrepancy, ensure Kia America and the dealer produce verifiable proof of completion, and confirm that the federal record is corrected. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA complaint #11697664 — an unverified report by a vehicle owner.

ENGINE

I’ve had my car for 6 months and it constantly burns oil I’ve had 4 oil changes because it Is completely disappearing but my mechanics can not find any leaks. Then I changed all my spark plugs and two were completely burnt and they were changed a month ago and now one of them went again and this time is completely covered in oil

NHTSA complaint #11691928 — an unverified report by a vehicle owner.

ENGINE

The engine of my 2018 Kia Optima is burning oil. When it started, I had 72,000 miles, and it's burning one quart of oil every thousand miles. There is no oil leak. I will take it back to Kia on October 2, 2025. The mechanic reported that it has an internal engine issue.

NHTSA complaint #11690169 — an unverified report by a vehicle owner.

ENGINE

The oil consumption is burning at a faster rate than normal. My oil changes are always on time but for months I have been having to take it for an oil change about 2,000 miles below mileage time. I have had it inspected but found no oil leaks. This is a major problem for the engine and safety.

NHTSA complaint #11689592 — an unverified report by a vehicle owner.

ENGINE

Engine seized and stopped working. While I could not find any recall information based on the VIN, it is a 2018 Kia which was subject to the Kia Engine Settlement (In re: Hyundai and Kia Engine Litigation , No. 8:17‑cv‑00838‑JLS‑JDE and Flaherty v. Hyundai Motor Company, et al. , No. 18‑cv‑02223 (C.D. Cal.)). Was never notified of such settlement as the VIN would have triggered this notification by Kia but they obviously did not list this in the recall.

NHTSA complaint #11689026 — an unverified report by a vehicle owner.

ENGINE

I was driving on the highway with my children and the engine started to knock and lock up. I had to swerve onto an exit and roll into a gas station. My check engine light was on. I had it serviced in 2023 at a kia dealership. I had electrical issues to my battery that I opted to get fixed elsewhere. The dealership was aware of the recall on my engine, when I had it towed to them in 2025. Dealership said I opted out of a recall on my engine.

NHTSA complaint #11688052 — an unverified report by a vehicle owner.

ENGINE

Car would convulse and shake very wildly metal parts spread around engine. It has very rough idle. 4th cylinder went out and car only has about 99060 miles. The valve went out. My safety was very bad as car was not driving safely and shaking like a person having a seizeure each time it would stop. Vehicle has been inspected by a Kia dealer. This problem I had seems to get an issue many other people with Kia Optima have.

NHTSA complaint #11687988 — an unverified report by a vehicle owner.

ENGINE

My 2018 Kia Optima has a cracked oil pan, which caused an excessive oil leak —up to 5 quarts in a matter of hours. This eventually led to my engine going out.

NHTSA complaint #11685738 — an unverified report by a vehicle owner.

ENGINE

Car suddenly stopped working; it was struggling to stay on. Mechanic stated cylinder is not functioning at full force.

NHTSA complaint #11684905 — an unverified report by a vehicle owner.

ENGINE AND ENGINE COOLING

The contact owns a 2018 Kia Optima. The contact stated that while driving at various speeds, the vehicle hesitated while depressing the accelerator pedal with the oil warning light flashing on the instrument panel. The contact's friend initially inspected the vehicle and discovered that the engine oil was empty. The vehicle was taken to a dealer where a diagnostic test was performed, and the mechanic discovered oil around the engine; however, the source of the leak was not discovered. The contact was informed that an engine valve was sealed and that the failure was repaired. Despite the repair, the failure persisted, and the oil light was frequently illuminated on the instrument panel. The engine oil level was checked and was extremely low. The dealer had not offered any additional assistance for the repair. The vehicle was not repaired. The contact made several attempts to reach the manufacturer but was unsuccessful. The failure mileage was approximately 10,000.

NHTSA complaint #11681328 — an unverified report by a vehicle owner.

ENGINE

My 2018 Kia Optima went into limp mode while exiting the freeway. I had it scanned and received a P1326 code, which is directly tied to the known engine knock sensor / bearing wear issue in Kia models. The engine light came on and the car lost power suddenly. This created a very unsafe situation. I contacted Kia, and they confirmed that my VIN is not included in the engine recall (KSDS campaign), even though my symptoms exactly match the covered vehicles. I am now stuck with an undriveable car and no recall coverage, even though I’m facing the same failure risk. I believe this VIN should be included, and that this is a clear safety issue. I am requesting the NHTSA to investigate and push Kia to expand coverage to include more affected vehicles.

NHTSA complaint #11678073 — an unverified report by a vehicle owner.

ENGINE

My 2018 Kia Optima LX began using excessive oil (>3 quarts/1000 miles) just over 100K miles. I researched and found that the Theta II engine in my car is known for this. When I took my car to dealership (Stokes Hodges Kia, North Augusta, SC), with the check engine light on, they told me me plugs were fouled (they were just replaced 1 yr prior), cylinder 3 misfiring, and that I needed to pay a few thousand dollars to have repaired. When I asked them to guarantee the soaking process they recommended, they responded that they couldn't, that it "only worked 80% of the time." I have the KSDS download since 2019 and asked them to follow the guidelines of their TSB ENG 222 for the class action lawsuit and start a 1000 mile oil consumption test. they refused, basically telling me the only way to get a new engine from Kia, since my car is over 100K miles, is to drive it until the engine seizes. I expressed my fear for personal safety, but they wouldn't help me. I am original owner and have all services, etc documented. I called Kia customer affairs, then was told only local dealership could help. they stuck me in a loop between them without helping. Please help me.

NHTSA complaint #11674425 — an unverified report by a vehicle owner.

ENGINE

Kia is aware of the engine oil consumption causing misfires, failed emissions test, blowing a rod and engine lock up. THEIR SOLUTION WAS A CLASS ACTION LAWSUIT THAT STATE ONCE THE CAR IS LOCKED UP OR ROD HAS BLOWN THROUGH THE ENGINE THEN THEY WILL FIX IT. I HAVE HAD TO ADD OIL AT LEAST 3 TIMES EVERY 3000 MILES AND CONTINUE TO REPLACE THE OIL FILTER AS WELL. THE SPARK PLUGS HAVE BEEN REPLACED MUTLIPLE TIMES ALSO TO HELP WITH THIS ISSUE. KIA ADVISED THAT MY VEHICLE DID NOT FALL UNDER THIS RECALL EVEN THOUGH MY VEHICHLE IS HAVING THE SAME ISSUES AS THE RECALL STATES. THIS IS A KNOWN ISSUE WITH THIS MAKE AND MODEL AND THEY SHOULD NOT BE ABLE TO GET AWAY WITH SELLING DEFECTIVE VEHICLES AND NOT REPAIRING THE ISSUES THEY KNEW THEY HAD PRIOR TO SELLING THE VEHICLES. SOMETHING NEEDS TO BE DONE.

NHTSA complaint #11673608 — an unverified report by a vehicle owner.

ENGINE

Engine failed despite maintenance and repairs. The car is part of the active class action for Kia Engine Defects. The KSDS software was never installed as we were never notified about the recall by kia. As a result, Kia denied coverage under the engine defect class action settlement. We need this vehicle repaired or compensation for replacement

NHTSA complaint #11672753 — an unverified report by a vehicle owner.

ENGINE

The car is literally burning through oil so bad every other week I am putting more in, the electrical system continues to fail and shorts, the motor sounds like it is ticking now due to the oil consumption.

NHTSA complaint #11672225 — an unverified report by a vehicle owner.