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 2018 Kia Optima owners, lightly cleaned up (personal details are redacted by NHTSA).
The contact owns a 2018 Kia Optima. The contact stated that while his wife was driving at an undisclosed speed, the vehicle went into LIMP Mode, and the check engine warning light was illuminated. The vehicle was restarted; however, the failure recurred while driving. The vehicle was taken to the dealer, where it was diagnosed and determined that the spark plugs had failed and needed to be replaced. The vehicle was repaired; however, the failure recurred while driving. The vehicle was towed to the dealer, where it was diagnosed that the engine had failed and needed to be replaced. The contact was informed by the dealer that the repair could not be covered due to the poor maintenance of the vehicle; however, upon providing all the maintenance records, the dealer informed the contact that the vehicle could not be repaired unless the engine had fully seized. …
The contact owns a 2018 Kia Optima. The contact stated while driving approximately 40 MPH, the accelerator pedal was depressed; however, the vehicle failed to respond as needed. The contact stated that there was an abnormal growling sound coming from under the floorboard, and the engine was making an abnormal knocking sound. The contact stated that the RPM gauge was revving high while depressing the accelerator pedal; however, the vehicle failed to respond. The contact pulled over and turned off and restarted the vehicle; however, the vehicle was not running normally. The contact stated that the failure was a recurring failure. Additionally, the contact stated that vehicle was consuming approximately one quart of engine oil per week and the transmission was hesitating and was making the vehicle jerk while shifting gear. …
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 owns a 2018 Kia Optima. The contact stated while driving approximately 40 MPH, the vehicle was losing motive power. The contact stated that there were no warning lights illuminated. The contact stated that the vehicle stalled. The contact was able to stop; however, after numerous attempts to restart the vehicle, the contact had the vehicle towed to the residence. The vehicle was later towed to a local dealer who inspected the vehicle and determined that the engine had seized and needed to be replaced. The contact stated that prior to the stall, the vehicle had been consuming an abnormal amount of engine oil. The contact stated that he was adding a quart of oil every week. The vehicle was not repaired. The manufacturer was informed of the failure. The contact researched online and related the failure to NHTSA Campaign Number: 17V224000 (Engine and Engine Cooling). …
The contact owns a 2018 Kia Optima. The contact stated that the vehicle was experiencing abnormal oil consumption. The contact stated that on one occasion, 3 quarts of oil were added to the vehicle after less than 1,000 miles of driving. The vehicle was taken to the dealer who initiated an oil consumption test. The vehicle was taken back to the dealer twice after 1,000 miles; however, upon returning to the dealer the third time, the dealer informed the contact that they could not complete the oil consumption test because the vehicle had been driven 1,200 miles. The dealer initiated another oil consumption test. The contact stated that the local dealer was 45 miles away from his residence, which made it difficult to complete the oil consumption test. The vehicle was not diagnosed or repaired. The manufacturer was notified of the failure, but no assistance was provided. …
The contact's sister owns a 2018 Kia Optima. The contact stated that the vehicle was consuming an excessive amount of engine oil. The contact stated that engine oil needed to be added every 2-3 weeks. The contact stated that an unknown warning light was illuminated. The vehicle received an unknown repair; however, the failure persisted. The vehicle was taken to the dealer and was diagnosed with valve cover gasket failure. The valve cover gasket was replaced however, the failure persisted. The failure persisted and the vehicle was taken to an independent mechanic where it was discovered that there was an oil leak as well as there was excessive oil consumption. The independent mechanic stated that the engine might need to be replaced; however, a diagnostic result was not confirmed. The vehicle had not been repaired. The manufacturer was not made aware of the failure. …
The contact owns a 2018 Kia Optima. The contact stated while driving 60 MPH, the vehicle went into Limp Mode. The check engine warning light illuminated. The vehicle was taken to the dealer where the failure was diagnosed as a faulty knock sensor that needed a software update. The vehicle was repaired. The contact stated that after receiving the vehicle from the dealer the vehicle was slow to accelerate and the vehicle was driving sluggishly. The contact stated that the vehicle needed to be taken back to the dealer to be diagnosed and repaired. The contact related the failure to the Kia Consent Order with NHTSA; however, the 2018 Kia Optima was not included. The contact stated that the remedy was not sufficient to remedy the vehicle failure. The manufacturer was notified and a case was opened. The failure mileage was 62,709.
The contact owns a 2018 Kia Optima. The contact stated that while driving 35 MPH after leaving the dealer, the vehicle started to overheat. The contact stated that the high engine temperature warning light was illuminated. The contact was able to safely pull over and turn the vehicle off. The contact restarted the vehicle and the engine temperature was still elevated. The contact stated that the vehicle stalled in the middle of the roadway. The vehicle was left on the side of the roadway. The vehicle was taken to the local dealer and diagnosed; however, the contact was not provided the diagnostic result. The contact was informed by the mechanic of an unspecified engine failure. The vehicle was not repaired. The manufacturer had not been informed of the failure. The failure mileage was approximately 77,200.
The contact owns a 2018 Kia Optima. The contact stated that while driving at various speeds, the contact noticed an abnormal oil consumption. The check engine warning light was intermittently illuminated. The vehicle was taken to a local dealer, where it was diagnosed with a spark plug misfire. The vehicle was repaired; however, the failure persisted. The vehicle was towed to a local independent service center, and the spark plugs were replaced. The contact stated that the vehicle was taken to a local independent mechanic where it was repaired several times; however, the failure reoccurred. The vehicle was taken to a second local independent mechanic, where the spark plugs and other unknown repairs were made. The manufacturer was made aware of the failure. The failure mileage was approximately 100,000.
The contact owns a 2018 Kia Optima. The contact stated that while driving 65 MPH, the check engine warning light illuminated, and the vehicle shuddered and stalled. The contact was able to pull over to the side of the road. The vehicle was able to restart but was shuddering significantly. The vehicle was towed to the dealer, where it was diagnosed with a fractured valve in cylinder #1. The dealer determined that the engine needed to be replaced. The vehicle was not repaired due to the cost. The manufacturer was notified of the failure and confirmed that the maintenance records of the vehicle were satisfactory; however, the manufacturer denied assistance and informed the contact that the failure was not a factory defect but was due to wear and tear. The failure mileage was approximately 109,000.
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 2018 Kia Optima?
NHTSA has 143 complaints about the engine & cooling of the 2018 Kia Optima, 62% of the model year's 232 complaints. The component named most often is engine › oil/lubrication (2 mentions).
Is there a recall for 2018 Kia Optima engine problems?
No. NHTSA lists no engine & cooling recall for the 2018 Kia Optima, though it has 2 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 2018 Kia Optima engine problems start?
Half of the complaints with a recorded mileage happened before about 73,000 miles, and 26% before 25,000 miles.
Is it dangerous?
Owners linked 1 crash, 9 fires and 0 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.