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 Oct 2, 2026

143 of the 232 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.

No recall on this systemas of Oct 2, 2026

No crash reportedin 52 reports

1 firein 52 reports

NHTSA investigation1 covering the 2018

Tick what matches of 52 reports

a knocking or ticking noise first

the engine seized

oil light or low oil

the engine was replaced

it was covered by a warranty or extension

I was denied coverage

Engine failure on other Optima years

2014129 reports 2015319 reports 2016201 reports 201772 reports 201852 reports 201933 reports 202044 reports

Report counts are for each model year on its own, so a newer car has had less time to collect them.

What this problem usually is

These are the reports nobody wants to file. The engine started knocking or ticking, the oil light came on, and then it seized or had to be replaced. Some owners had the replacement covered under warranty or an extension, and plenty were told they'd pay. Several narrower sheets split this group into knocking, seized engines and rod bearing failure.

Read the full explainer · Which cars report it most

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 Oct 2, 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.

EA21-003opened Dec 22, 2021

Engine · model years 2011 to 2017

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

RQ17-003opened May 18, 2017

Engine · model years 2011 to 2014

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

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.

Is this a known problem?

The manufacturer has sent NHTSA 19 service bulletins or notices for the 2018 Kia Optima that deal with this problem. Newest first.

Federal rules make a manufacturer send NHTSA a copy of any notice about a defect that goes to more than one dealer or owner. Most of these are service bulletins, the repair instructions manufacturers send to dealers. NHTSA generally leaves safety recall bulletins out of this file, and recalls are listed separately.

Service bulletinPI1802YZ_TSB_R7Mar 22, 2024
PRODUCT IMPROVEMENT CAMPAIGN: ENGINE REPLACEMENT INSTRUCTIONS FOR DTC P1326 (PI1802Y/Z) This bulletin provides information related to the Technical Service Bulletin previously published PI1802 titled "Knock Sensor Detection System - ECU Logic Improvement"; equipped w/THETA II engine.
Service bulletinPS720Apr 20, 2022
PITSTOP: INJECTOR HARNESS ROUTING FOR PI1802Y/Z AND PI1803Y/Z ENGINE REPLACEMENTS This bulletin provides information to address a no-start or hard start with poor running condition after engine replacement under PI1802Y/Z or PI1803Y/Z. Some replacement long blocks may come with pre-installed fuel rail, injectors, and injector wiring ...
Service bulletinPI1802YZ_TSB_R6Dec 23, 2021
ENGINE REPLACEMENT INSTRUCTIONS FOR DTC P1326 (PI1802Y/Z) This bulletin provides information related to the Technical Service Bulletin previously published PI1802 titled "Knock Sensor Detection System - ECU Logic Improvement" equipped w/THETA II engine.
Service bulletinPI1802_TSB_R12Aug 4, 2020
PRODUCT IMPROVEMENT TSB_PI1802_R2 - Knock Sensor Detection System - ECU Logic Improvement - This bulletin provides information related to a software update to the Engine Control Unit (ECU) to install the Knock Sensor Detection System (KSDS) in order to protect the engine from ...

15 more on the 2018 Kia Optima page.

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. How reports land on this sheet.

Guide Taking it to a shop? How to describe this problem so it gets found