Engine knocking and stalling on interstate
2020 Kia Optima
Owner reports · Recalls · Investigations
Similar to other model years
Owner complaints for the 2020 Kia Optima do not stand out strongly from the model-year median of 186.5.
About this comparison →How this year compares
Owner complaints by model year
Compare all Optima years →Counts vary with age, sales and reporting. They are not failure rates.
What owners reported most
All reported categories
Tap a category to read its complaints. One report may name several components.
When problems were reported
Mileage at the reported incident
Limited mileage data: 27 of 145 reports include usable mileage. There isn’t enough coverage to show a useful chart.
NHTSA’s mileage field refers to the reported incident, not necessarily the filing date. This shows report counts, not the likelihood of a failure.
What to inspect
Issues worth paying extra attention to based on owner reports.
- Engine. Review the 98 owner reports in this category and discuss these concerns during a pre-purchase inspection. Read reports →
- Power Train. Review the 26 owner reports in this category and discuss these concerns during a pre-purchase inspection. Read reports →
- Electrical System. Review the 13 owner reports in this category and discuss these concerns during a pre-purchase inspection. Read reports →
NHTSA owner reports · September 18, 2026 snapshot.
Power Train complaints
26 reports2020 Kia Optima LX 2.4, LESS THAN 100,000 miles on car. Car started over consuming oil 2 quarts/1,000 miles. Cranked engine yesterday to go to work and serious knocking sounds, engine is rattling severely. Losing revving power, undriveable. Smoke coming out of exhaust that smells like rotten eggs. Will be taking this to get code…
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2020 Kia Optima LX 2.4, LESS THAN 100,000 miles on car. Car started over consuming oil 2 quarts/1,000 miles. Cranked engine yesterday to go to work and serious knocking sounds, engine is rattling severely. Losing revving power, undriveable. Smoke coming out of exhaust that smells like rotten eggs. Will be taking this to get codes run but I believe this is due to Theta II engine failure issue reported in similar cars with the same engine. KIA NEEDS TO COVER THE 2020 OPTIMA UNDER LIFETIME WARRANTY PROTECTION otherwise this is a $10,000 cost to replace engine.
When the vehicle was about 3 years old and at 60,000 miles, the fuel injector went out. Kia took weeks to approve the replacement under warranty. Since then the engine light came on and said cylinder 3 has leak and fouls the plug. We've had it repaired 3 times. The mechanic said it would be too costly to repair and the engine sh…
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When the vehicle was about 3 years old and at 60,000 miles, the fuel injector went out. Kia took weeks to approve the replacement under warranty. Since then the engine light came on and said cylinder 3 has leak and fouls the plug. We've had it repaired 3 times. The mechanic said it would be too costly to repair and the engine should be replaced.
Accelerating at a normal rate to get on the highway and the check engine light starts flashing out of nowhere and car goes into limp mode. Made it to local shop and they informed me it was a P1326 code and that a knock sensor would have to be replaced, but that Kia has recalled the older models for this same reason.
I am filing this complaint due to severe and ongoing safety defects in my 2020 Kia Optima EX, which has repeatedly stalled while driving, creating a life-threatening road hazard. Since September 2024, my vehicle has suffered from major failures, including a complete transmission replacement, multiple high-pressure fuel pump rep…
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I am filing this complaint due to severe and ongoing safety defects in my 2020 Kia Optima EX, which has repeatedly stalled while driving, creating a life-threatening road hazard. Since September 2024, my vehicle has suffered from major failures, including a complete transmission replacement, multiple high-pressure fuel pump replacements, multiple oil flushes due to fuel contamination, and all fuel injectors replaced. Despite all of these “repairs” performed by a Kia-authorized dealership, the check engine light continues to return, and the vehicle still stalls unexpectedly, making it dangerous to drive. On March 10, 2025, after Kia claimed to have tested the vehicle for 200 miles, I picked up the car from the dealership, only for it to stall and trigger the check engine light within hours before I even reached my destination. This vehicle has been returned to me multiple times in an unsafe condition. Additionally, an independent mechanic discovered an engine oil leak and a torn axle that Kia’s dealership never disclosed. This raises major concerns about their lack of proper inspection and repair procedures. This is a serious safety issue that Kia refuses to take accountability for. I request an immediate investigation into this matter before this defect leads to an accident.
Code P1326 and oil pressure light keeps flashing
At gas, the vehicle jumps/judders as if it’s not getting enough gas to get up and go, and then at higher speeds it goes fine. Was reported to Horne Kia while under warranty. They never found the issues. Months later issue was found by a new mechanic, now the vehicle is no longer under warranty and the TRA codes are posted online…
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At gas, the vehicle jumps/judders as if it’s not getting enough gas to get up and go, and then at higher speeds it goes fine. Was reported to Horne Kia while under warranty. They never found the issues. Months later issue was found by a new mechanic, now the vehicle is no longer under warranty and the TRA codes are posted online. [XXX] Reported August 2021 [XXX] Reported December 2020 INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)
I was driving on the high way and the car loose power completely have to do change oil every two weeks and can’t find a solution
Was on highway going 65, check engine light started flashing loss power. Couldn't go over 2000 rpms car would struggle to accelerate, car had been using up oil like crazy the week before. Stopped at an autozone car read code P1326.
I started having clicking sound in engine around 50k miles . Then my check engine light came on and my engine has been using so much oil. I have to get an additional 3 quarts in between oil changes. The clicking sound is getting louder and my car is now having issues accelerating. . My engine is failing and I bought this car bra…
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I started having clicking sound in engine around 50k miles . Then my check engine light came on and my engine has been using so much oil. I have to get an additional 3 quarts in between oil changes. The clicking sound is getting louder and my car is now having issues accelerating. . My engine is failing and I bought this car brand new and have regularly maintained it .
Official recalls
0No recalls in this snapshot.
Model-level recall history does not show whether a particular VIN is affected or has received a repair. Check a VIN with NHTSA ↗
NHTSA investigations
1DP22003 · Loss Of Motive Power
Opened Sep 12, 2022 · Closed Dec 12, 2023
Status: closed (inferred from source dates) · Engine
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. The Petitioners cited examples of complaints indicating that the subject vehicles were experiencing rapid loss of engine oil due to oil drain plug back outs, resulting in loss of motive power and/or catastrophic engine damage. Additional complaints were provided which alleged that the oil drain pans lack sufficient structural integrity and are susceptible to cracking. The petition itself can be reviewed at NHTSA.gov under ODI number 11481745. On September 12, 2022, the Office of Defects Investigation (ODI) opened Defect Petition (DP22-003) to evaluate the Petitioners’ request. The Petitioners have provided additional complaints within four supplemental letters dated January 31, 2023, March 21, 2023, May 23, 2023, and August 4, 2023. ODI’s evaluation included the review and analysis of the complaints and supporting information submitted by the Petitioners, as well as additional complaints submitted directly to NHTSA which referenced either the oil drain plug or a crack in the oil pan. After reviewing the available data, ODI has not identified evidence that would support opening a defect investigation into the oil drain pan assemblies of the subject vehicles. Based on a review of the available information, a loss of motive power resulting from an oil drain plug back out has not occurred between the initial sale of a vehicle and the completion of its first oil change. If during an oil change service, a technician fails to remove the existing drain plug gasket before installing a new gasket, it is likely that a proper seal between the drain plug and the oil pan will not be made. An improper seal between the drain plug and oil pan could lead to the backing out on the drain plug, resulting in the sudden loss of oil while driving. Additionally, the provided examples of oil pan cracks were localized to the immediate vicinity of the oil drain plug and/or appeared to be the result of direct-contact with a tool during servicing. There is no information to support that a vehicle-based defect exists relating to the oil pan assembly, and instead the documented incidents are related to the failure to follow the proper maintenance procedures during oil change service. In October 2023, Hyundai published a Technical Service Bulletin (TSB) that provided detailed instructions for oil change service on its gasoline powered vehicles, specifically highlighting the need to remove and replace the existing drain plug gasket prior to reinstalling the drain plug. After a thorough review of the material submitted by the petitioner, the information already in NHTSA's possession, and the potential risks to motor vehicle safety implicated by the petitioners' allegations, NHTSA does not believe that a formal investigation is warranted. Therefore, the petition is denied. A Federal Register Notice (FRN) further detailing NHTSA’s reasons for denial of the petition will be published. The reference numbers for the complaints to NHTSA cited by the petitioner can be found in the petition submission documents in the public file for DP22-003. To review those complaints and the additional complaints ODI added to its evaluation which are cited in the Closing Resume ODI Report Identification Number document, go to NHTSA.gov.
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