VOLUNTARY EMISSIONS SERVICE CAMPAIGN: OWNER NOTIFICATION (SC340 FLIGHT 104 ) - This document is the owner notification advising that Kia is conducting a Voluntary Emissions Service Campaign to improve the emissions software logic in the Electronic Control Module (ECM) for certain 2016-2020 MY Optima vehicles equipped with 2.4L Gas Direct Injection (GDI) engines to ensure compliance with emissions regulations.
full bulletin at NHTSA ↗2018 Kia Optima electrical problems
severe Owners of the 2018 Kia Optima have filed 27 NHTSA complaints about the electrical at roughly $850 to repair (U.S. federal records, as of July 2026). Source: NHTSA Office of Defects Investigation. See electrical across all vehicles →
Complaints
27
Recalls
0
Avg fix
$850
| Model year | electrical complaints |
|---|---|
| 2014 Optima | 50 |
| 2015 Optima | 104 |
| 2016 Optima | 78 |
| 2017 Optima | 24 |
| 2018 Optima (this page) | 27 |
| 2019 Optima | 18 |
| 2020 Optima | 11 |
2fires
What stands out
Owners have filed 27 electrical complaints with NHTSA against this vehicle, but no formal recall covers the issue — the federal record reflects what manufacturers have admitted, not everything owners are reporting.
Is there a fix? Manufacturer service bulletins
The manufacturer has issued service bulletins covering electrical on this vehicle — documented repair instructions, service campaigns, or warranty extensions sent to dealers. A TSB isn't a recall (it's not a free safety remedy), but it's the manufacturer acknowledging the issue and how to fix it.
TECHNICAL SERVICE BULLETIN: VOLUNTARY EMISSIONS SERVICE CAMPAIGN: THETA II 2.4L GDI EMISSION SECM LOGIC IMPROVEMENT (SC340 REV 4) - This bulletin has been revised to include additional information. New/revised sections of this bulletin are indicated by a black bar in the margin area. This bulletin provides information to upgrade the Electronic Control Module ‘ECM’ system software for certain 2016-2022MY vehicles equipped with 2.4L Theta II engines listed in the table below. Kia has become aware that certain 2016-2022MY vehicles equipped with 2.4L Theta II engines may have engine calibrations that were not optimized for emissions standards under certain specific conditions. These calibrations
full bulletin at NHTSA ↗VOLUNTARY EMISSIONS SERVICE CAMPAIGN: DEALER PRINCIPAL MEMO (SC340) - This document is the announcement to the dealer principals advising that Kia is conducting a Voluntary Emissions Service Campaign to improve the emissions software logic in the Electronic Control Module (ECM) to ensure compliance with emissions regulations in certain 2017-2022 MY Sportage vehicles manufactured from December 10, 2015, through December 7, 2021, certain 2016-2020 MY Optima vehicles manufactured from August 28, 2015, through June 23, 2020, and certain 2016-2020 MY Sorento vehicles manufactured from October 27, 2014, through November 4, 2020, equipped with 2.4L Theta GDI engines.
full bulletin at NHTSA ↗VOLUNTARY EMISSIONS SERVICE CAMPAIGN: DEALER PARTS AND SERVICE MANAGER MEMO (SC340) - This document is the announcement to the dealer Parts and Service managers advising that Kia is conducting a Voluntary Emissions Service Campaign to improve the emissions software logic in the Electronic Control Module (ECM) to ensure compliance with emissions regulations in certain 2017-2022 MY Sportage vehicles manufactured from December 10, 2015, through December 7, 2021, certain 2016-2020 MY Optima vehicles manufactured from August 28, 2015, through June 23, 2020, and certain 2016-2020 MY Sorento vehicles manufactured from October 27, 2014, through November 4, 2020, equipped with 2.4L Theta GDI engines.
full bulletin at NHTSA ↗VOLUNTARY EMISSIONS SERVICE CAMPAIGN: SC340_POC: PROOF OF CORRECTION CARD
full bulletin at NHTSA ↗Source: NHTSA manufacturer communications. Bring the bulletin number to your dealer or shop.
The failure pattern owners describe
Owners describe a pattern of electrical failures that dealerships struggle to diagnose and repair. The most alarming involve safety systems: headlights turning off unexpectedly while driving at night, complete loss of power steering and brake response, parking sensors missing pedestrians, and doors locking automatically while the engine runs—trapping drivers outside their vehicles multiple times.
Engine-related electrical issues are widespread: stalling that recurs within days of repairs for spark plugs, ignition coils, valve cover gaskets, and fuel systems; oil consumption so severe the warning light comes on every 800–1,000 miles; and one vehicle that caught fire after smoking sparked under the car.
Owners also report headlight bulbs exploding with burning connections, passenger seat belt warnings activating on an empty seat, trunk latches failing and trunk open indicators not working, and a recall completion discrepancy where the dealership and Kia claim work was done but NHTSA's database still shows the recall incomplete.
Repeated service visits are a common thread—technicians consistently claim they cannot reproduce issues in the shop, leaving owners stranded with unresolved safety concerns. One owner's multi-point inspection summary was particularly brutal: dealership called the vehicle "basically trash" while the owner still owed $7,000 on the note.
Same Kia Optima electrical reports on nearby years: 2015 · 2016 · 2017 · 2019 · 2020
Failure modes owners describe
Unintended door lock-up with engine running
Doors lock automatically while engine is running and vehicle is in park, trapping the driver outside. Occurs unpredictably when filling gas, warming up, or idling. Dealership unable to reproduce the issue on multiple visits.
When: Random; occurs at gas stations and while warming vehicle
Symptoms owners cite: All doors lock while engine running in park; Driver locked out of vehicle; No warning before doors lock; Requires spare key or second set to access vehicle
Repairs/costs cited: No repairs performed; dealership unable to reproduce issue despite multiple visits
False passenger seat belt warning with empty seat
Passenger seat belt audio warning activates repeatedly while the front passenger seat is unoccupied. Warning continues until seat belt is latched over empty seat. Owner concerned about potential cross-wiring affecting passenger airbag deployment logic.
When: Approximately one year into ownership; began after 2 years of normal operation
Symptoms owners cite: Seat belt warning chimes while passenger seat is empty; Warning only stops when belt is latched over empty seat; No occupancy sensor triggering; Issue recurred at least twice after service visit
Repairs/costs cited: Dealership inspected wiring, found no obvious fault, performed no further testing
Repeated stalling and engine shutdown
Vehicle stalls and shuts off unexpectedly while driving and at idle. Battery replaced twice. Mechanics diagnosed faulty spark plugs, ignition coil, valve cover gasket leak, and fuel system issues. Despite multiple repairs, shutdowns continue and recur within days to weeks of each repair.
When: Ongoing since purchase; January issue prompted shop visit; recurrences within 1 month and less than 1 week of repairs
Symptoms owners cite: Unexpected shutdown while driving; Stalling at idle and in drive-thru; Vehicle shakes before shutdown; Poor acceleration; Excessive oil consumption
Codes mentioned: P0303, P0456, P123300
Repairs/costs cited: Spark plugs and ignition coil replaced; valve cover gasket replaced; belts replaced; fuel system cleaned—all completed within months but stalling persists
Recall SC218 reporting discrepancy
Dealership and Kia America claim recall SC218 (engine inspection and KSDS software update) completed in August 2025, but NHTSA database shows recall remains incomplete. Multiple internal records and warranty documents conflict with federal database. Owner reports lack of verifiable documentation.
When: August 2025 dealership service; discrepancy discovered September–November 2025
Symptoms owners cite: Recall marked completed on dealer RO and Kia America email; NHTSA VIN lookup shows recall incomplete; No diagnostic data or Battery SOH report provided to owner
Repairs/costs cited: Dealership claims ECU software update performed; Kia America confirms update under case number
Recalls/TSBs owners mention: Kia America emailed confirmation of completed SC218 with software update reference, but federal NHTSA database contradicts this
Multiple electrical system failures with brake and steering loss
Vehicle experiences simultaneous failure of multiple electrical systems: brake booster failure, loss of power steering, brake pedal unresponsive. Multiple warning lights illuminate (power steering, battery, warning light, airbag, ABS, traction control). Results in loss of braking capability while backing and during normal driving.
When: Onset after short trip to store; second multi-point inspection at dealership after separate incident months later
Symptoms owners cite: Brake pedal becomes hard or unresponsive; Loss of power steering; Multiple dash warning lights illuminated simultaneously; Backup camera flickering; Oil warning light intermittent; burning oil smell; Unable to shift vehicle into gear initially
Repairs/costs cited: Dealership identified brake booster failure and low engine oil; owner reports 'car is basically trash' assessment; still owes $7,000
Widespread electrical system failure affecting multiple subsystems
All electrical indicators illuminate at once (brake, steering, check engine, airbag, ABS, traction control); dash flashing. Vehicle unable to shift and loses power steering. Dealership unable to diagnose cause.
When: Sudden onset after returning home from store
Symptoms owners cite: Dash flashing; Multiple warning lights on simultaneously; Unable to shift from park; Loss of power steering; Vehicle moves but requires park release shift override
Repairs/costs cited: Dealership refused to diagnose without additional charges; stated cause unknown; suspected operator asked about lightning strike
Recalls/TSBs owners mention: EPD recall mentioned by owner as existing for hybrid models only per dealership claim
Headlights turning off and on randomly
Headlights turn off and on by themselves while vehicle is in motion, particularly at night. AUTO setting switches to OFF without driver input. Jiggling turn signal switch or manually cycling switch may restore lights. Frequency increasing and becoming a safety concern. Technicians unable to reproduce issue.
When: Random; different times and locations; occurring more frequently over time
Symptoms owners cite: Headlights turn off unexpectedly while driving at night; Dash display switches from AUTO to OFF without driver action; Lights may restore if turn signal switch jiggled; Manual cycling of headlight switch required to restore lights; Increasing frequency
Repairs/costs cited: Vehicle in for service multiple times but technician unable to reproduce issue
Trunk will not close and latch failure with missing open indicator
Trunk latch fails; trunk will not close or remain closed. Trunk open indicator does not illuminate on dash when trunk is open, creating hazard when driving. Owner had to bungee trunk closed.
When: Unknown timing; discovered during driving when trunk flew open
Symptoms owners cite: Trunk latch non-functional; Trunk will not close; Trunk open indicator does not blink when trunk is open; Trunk flies open while driving
Repairs/costs cited: Trunk bungee-corded closed by owner; no dealership repair mentioned
Starting difficulty and battery drain with electrical lock-up
Vehicle hesitates when starting; eventually all dash lights illuminate but no ignition occurs. Steering and brake pedals lock up. Clicking noise heard. Jump start allows brief operation but vehicle fails to restart when turned off.
When: Intermittent hesitation; critical failure occurred after leaving car locked overnight with nothing left on
Symptoms owners cite: Hesitation on start attempts; All dash lights illuminate without ignition; Steering locked; Brake pedal locked; Clicking noise during attempted start; No restart after jump start and shutdown
Repairs/costs cited: Jump start attempted; requires dealership visit
Parking sensors failed to detect pedestrians
While reversing at low speed, rear and side parking sensors failed to detect two pedestrians walking past vehicle. No warning indicators illuminated. Dealership stated sensors operating as designed; no repairs performed.
When: At 14,356 miles
Symptoms owners cite: Sensors did not detect pedestrians in path of vehicle; No warning indicators illuminated; Pedestrians passed undetected
Repairs/costs cited: None; dealership stated sensors working as designed
Recalls/TSBs owners mention: Dealership stated sensors operating as designed; no further investigation
Excessive engine oil consumption
Engine burns oil at extremely high rate. Oil warning light illuminates within 800–1,000 miles of oil change. Dealership performed three separate tests; all failed and indicated faulty engine. Kia corporate denied warranty claim. Class action lawsuit ongoing in California.
When: Recurring at 800–1,000 miles after each oil change
Symptoms owners cite: Oil light comes on around 800 miles after service; Burning oil smell; Oil consumed completely within 1,000 miles
Repairs/costs cited: Three dealership tests performed; all indicated faulty engine
Recalls/TSBs owners mention: Kia corporate denied warranty claim despite dealership test results
Headlight bulbs failing and connections catching fire
Bulbs blow out repeatedly over two years. Some bulb connections catch fire and explode. Problem persists even with new bulbs and new fittings, indicating underlying electrical fault rather than bulb or socket issue.
When: Recurring over two-year period; multiple failures
Symptoms owners cite: Bulbs blowing out regularly; Bulb connections catching fire; Connections exploding; Problem continues with new bulbs and new fittings
Repairs/costs cited: Bulbs and fittings replaced multiple times; issue persists
Power loss while driving (Takara recall vehicle)
Vehicle power drops while driving at city street speeds (45 mph). Car becomes stationary in motion, then powers back on without driver turning ignition key. Described as scary and unexpected.
When: Single incident at 45 mph during city driving
Symptoms owners cite: Complete power loss while in motion; Vehicle resumes power without ignition input; Occurs at 45 mph on city street
Recalls/TSBs owners mention: Vehicle identified as Takara recall vehicle
Rough idle and engine kill without warning light
Engine runs rough at idle, chugs, and shuts off. No check engine light illuminates to warn driver. Has occurred multiple times.
When: Multiple occurrences; timing not specified
Symptoms owners cite: Rough idle; Chugging before engine dies; Engine shutdown; No check engine light warning
Complete headlight loss while driving at night
Headlights turn completely off while driving at night on highway. Occurs in AUTO mode. Multiple separate incidents reported.
When: Multiple incidents while driving at night
Symptoms owners cite: Headlights turn completely off; Occurs while driving at night on highway; Occurs in AUTO mode
Synthesized from 27 NHTSA owner complaints — unverified consumer allegations, summarized for patterns. The verbatim filings appear below.
What owners are reporting 0 most recent
Had electrical trouble with your 2018 Kia Optima?
File a complaint with NHTSA → It's free, official, and how every report above got here — owner filings are the federal safety record this page is built on.
Common questions
How serious is the electrical problem on the 2018 Kia Optima?
It's a meaningful issue. 27 complaints have been filed and the failure mode causes operational problems for owners. Repairs average $850.
At what mileage does the electrical typically fail?
Based on the 27 complaints filed, electrical issues most often appear around 22,745 miles. Some report problems earlier; some make it well past 150,000 with no symptoms. Maintenance habits matter — vehicles that received timely fluid services and were not regularly overworked tend to last longer.
What does it cost to fix?
Independent shops typically charge around $850 for electrical repairs on this vehicle. Dealer pricing tends to run 20-40% higher. The exact figure depends on the specific failure mode, parts availability, and your local labor rates. If you're outside factory warranty, an extended service contract often covers this category.
Are there any recalls related to electrical?
No active recalls currently cover electrical issues on this vehicle. The complaints filed represent owner-reported failures that haven't risen to the level of a manufacturer-issued recall — but they're still worth knowing about before you buy or budget for repairs.
Related
Complaint and recall data sourced from the National Highway Traffic Safety Administration (NHTSA)
public records database. Verify the raw federal record at
nhtsa.gov/vehicle/2018/Kia/Optima.
Severity ratings are derived from reported crashes, fires, injuries, and fatalities. Repair cost estimates are
independent-shop national averages and may differ in your area. Some links on this page are affiliate links.