Diagsheet

2018 Kia Optima · symptom sheet

Engine failure, knocking or rod bearing

  • 52owner reports
  • 64,000median miles
  • $686median quote
  • 0involved a crash

Newest report Aug 20, 2026 · checked Sep 9, 2026

142 of the 231 complaints on this car are about the engine. 52 of those describe engine failure, which makes it the most reported problem on the 2018 Optima.

Tick what matches of 52 reports

17
14
8
10
17
7

What got replaced

Owners who name the part that was replaced mention the engine (52 reports).

Recalls and investigations

No recall on the engine covers the 2018 model year as of Sep 9, 2026.

NHTSA investigations into the engine on the Optima

DP22-003opened Sep 12, 2022
Engine · model years 2005 to 2020

Loss of motive power. Closed dec 12, 2023.

NHTSA summary
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 as
EA21-003opened Dec 22, 2021
Engine · model years 2011 to 2017

Engine fires. Closed feb 5, 2024, led to recall 23V-877.

NHTSA summary
On March 29, 2019, the Office of Defects Investigation (ODI) opened two Preliminary Evaluations (PE19-003 on Hyundai and PE19-004 on Kia) to broadly investigate incidents of non-crash fires (regardless of origin or operational status of the vehicle) on various model year Hyundai and Kia vehicles. During the PE investigations, Hyundai and Kia issued several recalls to address vehicle fires, including those due to engine failures involving various engine types. The remedies for the engine failure recalls typically involve engine inspection (to detect existing damage), and if necessary, engine replacement. Additionally, both manufacturers have been installing an engine control software modification known as Knock Sensor Detection Software (KSDS) which is intended to detect impending engine failure, alert the driver, and limit engine power (to lessen likelihood of engine failure).KSDS is being installed under recalls and non-safety field actions, and both companies have extended limited engine warranties (see recall files). On December 22, 2021, ODI upgraded PE19-003 and PE19-004 to this Engineering Analysis (EA21-003, covering both Hyundai and Kia) to evaluate the scope of the prior recalls related to engine failures/fires and the efficacy of the recall remedies for the recalls, as well as the long-term viability of related programs and non-safety field actions being conducted by Hyundai and Kia. The former issue involved approximately 550,000 MY 2013 Hyundai Elantra, MY
RQ17-003opened May 18, 2017
Engine · model years 2011 to 2014

Scope and timeliness. Closed dec 22, 2021, led to recall 17V-224.

NHTSA summary
NHTSA opened Recall Query (RQ) 17-003 to investigate the timeliness and scope of Kia?s Theta II GDI engine recall (Recall No. 17V-224), and Kia?s compliance with reporting requirements. On November 23, 2020, the Agency entered into a Consent Order with Kia to administratively resolve NHTSA?s assertions of violations of law in connection with RQ17-003. NHTSA?s assertions included that Kia may be liable for civil penalties on multiple grounds, including that Recall No. 17V-224 was untimely and Kia?s recall report contained certain inaccuracies.Under the Consent Order, Kia agreed to a total civil penalty of $70,000,000. The total civil penalty included a payment of $27,000,000 as a Non-Deferred Amount.Kia also agreed to a sum of $27,000,000 as an Abeyance Amount to be deferred and held in abeyance pending its satisfactory completion, as reasonably determined by NHTSA, of the requirements of the Consent Order.Kia also agreed to a $16,000,000 Performance Obligation Amount to be expended by Kia to fulfill specified Safety Data Analytics Infrastructure obligations. The Consent Order also includes other terms designed to enhance Kia?s safety practices, and requires Kia to retain a Third-Party Auditor who directly reports to NHTSA.Other than RQ17-003, the Consent Order is not intended to affect any other current or future investigation of NHTSA which may involve vehicles equipped with Theta II GDI engines. In particular, Engineering Analysis (EA) 21-003 (which is upgraded from Prelimi

What owners paid

6 of the 52 reports quote a price. Each dot is one quote. The middle half runs $300 to $913.

$300$686$913
$0k$2k$4k$6k$8k

When it happens

The middle half of failures fell between 1,000 and 99,060 miles, from the 20 reports that gave a mileage.

120
121
722
823
1124
1725
726

What owners wrote

“Increased oil consumption with needing oil added and or changed half way before date or milage stated, oil changes performed by Kia dealer. Car staling and engine knocking while driving. Burnt smell while driving.”

Filed Dec 23, 2024

“Have completed 4 oil consumption tests and replaced knock sensor and now have knocking in the engine”

Filed Jul 16, 2024

“Engine continuously stalls,while driving in both city and hight way. I have taken it in while under warranty and am told that's just how the car runs. Sudden jerks / seizure will happen while driving. since I haven't gotten the vehicle it happens at min 15mph or on the freeway at 65 mph. It is stalls at all mph .”

Filed Jun 28, 2024

“My vehicle is constantly running out of oil within a 30 day period and I constantly getting an oil change. I was advised to get an oil consumption test at the dealer and was out of oil in 3 weeks. I was told that I have a warranty, however, it's only if the rod bearings are an issue. I think my engine should be replaced without paying a $300 diagnostic fee that might get refunded without an exact time frame.”

Filed Feb 23, 2024

Should you keep driving it?

This page can't tell you that. 0 of 52 reports involved a crash. Owners who file are the ones who had a bad experience, and nobody checks their reports. If the problem affects steering, braking, power or a fire risk, treat it as a safety fault and have it inspected before a long or high-speed drive.

File your own report with NHTSA. Complaint counts are how a problem gets an investigation.

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