2018 Kia Optima Complaints

AIR BAGS,SEAT BELTS — Filed 07/14/2026

I was run off the road by a drunk driver I hit a tree at 35MPH MY AIR BAGS DID NOT DEPLOY NOR DID MY SEAT BELT LOCK!!!! I NOW HAVE MULTIPLE INJURIES I HAVE BROKEN BONES ALL THROUGHOUT MY FACE!!!!! A SEVERE CONCUSSION!!!!! Any time I call the the customer care center and try and get information or call someone I either get hung up or gave the run around and then hung up on my mother in law has also tried calling and have received the same response this is so unacceptable and unprofessional.

ENGINE — Filed 05/23/2026

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

SERVICE BRAKES — Filed 01/06/2026

Purchased vehicle from a used car dealership. Had it a few months before brake pedal started losing pressure and going to floor. Had master cylinder replaced. A few months later, brake light started coming on when accelerating. New master cylinder had leaked into brake booster. Had master cylinder replaced along with brake booster. A few weeks later and brake pedal is losing pressure again

ENGINE — Filed 06/15/2026

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.

ENGINE AND ENGINE COOLING — Filed 08/29/2018

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.

UNKNOWN OR OTHER — Filed 06/09/2026

2018 Kia Optima Dealer Ed Voyles Kia Smyrna began Recall SC340. Vehicle drove in running. Dealer flashed ECM software, discovered non-original engine/ECU. Vehicle now won’t start. Dealer document states 'will not start after recall.' Dealer refuses to restore to running condition citing prior repairs. This violates 49 USC 30120

ENGINE AND ENGINE COOLING,LATCHES/LOCKS/LINKAGES — Filed 05/06/2026

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.

ENGINE — Filed 04/28/2026

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.

ENGINE — Filed 04/15/2026

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.

ELECTRICAL SYSTEM,UNKNOWN OR OTHER,FUEL/PROPULSION SYSTEM — Filed 03/17/2026

I am submitting this complaint regarding ongoing and persistent mechanical issues with my vehicle since the time of purchase. The vehicle has repeatedly shut off unexpectedly, creating a serious safety concern. Initially, I suspected the issue might be related to the battery, and I have replaced the battery twice within the past 4 years. However, the problem has continued. In January, the vehicle began shaking and shutting down again. I took it to a mechanic, who diagnosed the issue as faulty spark plugs and an ignition coil. The diagnostic codes provided were P0303 and P0456, and the recommended repairs were completed. Approximately one month later, the vehicle began shutting off again. I then took it to the dealership, where I was advised that the valve cover gasket needed to be replaced, along with the belts, and that a fuel system cleaning was required. I subsequently had these repairs completed by my mechanic. Less than a week after completing those repairs, the vehicle once again began shutting down. A diagnostic scan then produced code P123300. In addition to these repeated shutdowns, the vehicle consumes an excessive amount of oil, has poor acceleration, and continues to stall unexpectedly both while driving on the road and while idling, such as in a drive thru. These recurring issues have made the vehicle unreliable and unsafe. I am concerned about the risk of the vehicle shutting off while in motion, which could lead to a dangerous situation. I am requesting that this matter be reviewed for potential defects or safety-related concerns.