AI Damage2018 KIA Optima: common problems
Owners of the 2018 KIA Optima filed 233 complaints with NHTSA, most often about engine and electrical system. The maker issued 118 service bulletins for this year. Details by component below, with sources.
Key figures
- Owner complaints
- 233
- involving a crash
- 10
- Technical service bulletins (TSB)
- 118
What fails most often
- 1 Engine 57% of all complaints
- 2 Electrical system 14% of all complaints
- 3 Powertrain 8% of all complaints
- 4 Service brakes 7% of all complaints
- 5 Engine and cooling 6% of all complaints
- 6 Exterior lighting 6% of all complaints
- 7 Fuel/propulsion system 6% of all complaints
- 8 Steering 5% of all complaints
- Engine: 132 complaints (57% of all), 1 of them with a crash reported by the owner; manufacturer bulletins for this component: 18.
- Electrical system: 33 complaints (14% of all); manufacturer bulletins for this component: 35.
- Powertrain: 19 complaints (8% of all), 1 of them with a crash reported by the owner; manufacturer bulletins for this component: 17.
- Service brakes: 17 complaints (7% of all), 2 of them with a crash reported by the owner; manufacturer bulletins for this component: 2.
- Engine and cooling: 14 complaints (6% of all); manufacturer bulletins for this component: 38.
Engines and transmissions
US-market versions per EPA. On the right: how many NHTSA complaints name this engine or transmission type.
- 1.6 L · petrol · turbo · 4 cyl
- 2 L · petrol · turbo · 4 cyl
- 2.4 L · petrol · 4 cylnamed in 6 complaints
- 2 L · hybrid · 4 cyl
- 2 L · plug-in hybrid · 4 cyl
- automatic, 6-speed
- dual-clutch (DCT), 6-speed
- dual-clutch (DCT), 7-speed
Drive: FWD
Symptoms owners describe
How many of the 233 NHTSA complaints mention each symptom (automatic count from complaint text; one complaint can mention several).
Components owners complain about
| Component | Owner complaints | involving a crash | Technical service bulletins (TSB) |
|---|---|---|---|
| Engine | 132 | 1 | 18 |
| Electrical system | 33 | 0 | 35 |
| Powertrain | 19 | 1 | 17 |
| Service brakes | 17 | 2 | 2 |
| Engine and cooling | 14 | 0 | 38 |
| Exterior lighting | 14 | 0 | 2 |
| Fuel/propulsion system | 13 | 0 | 0 |
| Steering | 12 | 0 | 6 |
| Vehicle speed control | 10 | 0 | 0 |
| Air bags | 9 | 7 | 0 |
| Structure | 7 | 1 | 6 |
| Seat belts | 5 | 2 | 0 |
| Electronic stability control | 3 | 0 | 0 |
| Lane departure | 3 | 0 | 0 |
What owners report
Short excerpts of NHTSA complaints in the original wording. These are owner statements not verified by NHTSA; personal data removed.
I was run off the road by a drunk driver I hit a tree at 35MPH MY AIR BAGS DID NOT DEPLOY NOR DID MY SEAT BELT LOCK!!!! I NOW HAVE MULTIPLE INJURIES I HAVE BROKEN BONES ALL THROUGHOUT MY FACE!!!!! A SEVERE CONCUSSION!!!!!
No warning lights was illuminated. A police report was filed. No medical attention was sought, and no injuries were sustained. The vehicle was pronounced totaled at the scene. The contact attempted to contact the manufacturer however, received no response. The failure mileage was 96,145.
I hit the brakes and the brakes went to the floor multiple times and the car just searched straightforward into the brick wall of the building.
The frontal driver and passenger air bags did not deploy. The contact's daughter and the driver were injured and treated at a hospital. A police report was filed. The vehicle was destroyed and towed. The dealer and the manufacturer were not contacted. The failure mileage and vin were unknown.
In August 2026, the engine failed and the vehicle was taken to an authorized Kia dealer, where the engine was replaced under the Theta II engine warranty. The vehicle was at the dealer from August 8 until the repair was completed on September 29, 2026.
The contact stated that upon starting the vehicle, the vehicle jerked abnormally. The failure persisted while driving, and the vehicle lost motive power. The contact was able to restart the vehicle; however, the failure persisted while driving.
The vehicle was taken to an Auto Parts Store, where it was diagnosed, and it was determined that the vehicle was in LIMP Mode with knock sensor codes displayed. The vehicle was not repaired. The manufacturer was notified of the failure. The failure mileage was approximately 136,000.
The contact stated that while driving at an undisclosed speed, there was an abnormal odor and a knocking sound coming from the engine. The vehicle was taken to the dealer; however, the dealer was unable to duplicate the issue. The vehicle was not repaired. The issue persisted.
When owners complained
NHTSA complaints by filing year. The peak shows at what age the problems show up most.
Comparison
By complaint count this model year ranks 276 of 2,102 model years in the NHTSA data (top 13% most complained about).
On average one model year of the Optima has 323 complaints (5 years in the data). This year has 233, below average.
What to check before buying
- Engine. Cold start, unusual noises, oil leaks and engine codes.
- Electrical system. Scan all modules, test the battery and alternator, inspect connectors near the impact zone.
- Powertrain. Shift quality under load, harsh shifts, transmission codes, CV joints.
- Service brakes. Pedal feel, ABS operation, leaks, discs and hoses.
Manufacturer service bulletins
Bulletin titles as filed with NHTSA.
- TECHNICAL SERVICE BULLETIN
CUSTOMER SATISFACTION: THEFT DETERRENT IGNITION CYLINDER PROTECTOR AND DECAL INSTALLATION (CS2312) - This bulletin has been revised to include additional information. New/revised sections of this bulletin are indicated…
- VOLUNTARY EMISSIONS SERVICE CAMPAIGN
THETA II 2.4L GDI EMISSIONS: ECM LOGIC IMPROVEMENT (SC340 REVISION 5) - This bulletin has been revised to include additional information. New/revised sections of this bulletin are indicated by a black bar in the margin…
- 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…
- 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…
- CUSTOMER SATISFACTION CAMPAIGN
OWNER NOTIFICATION (CS2312) - This document is the owner notification advising that Kia is conducting Customer Satisfaction Campaign. A software upgrade that addresses the social media theft method has been made…
- VOLUNTARY EMISSIONS SERVICE CAMPAIGN
OWNER NOTIFICATION (SC340 FLIGHT 103 / JF) - 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…
- TECHNICAL SERVICE BULLETIN
CUSTOMER SATISFACTION: THEFT DETERRENT IGNITION CYLINDER PROTECTOR AND DECAL INSTALLATION (CS2312) - This bulletin provides information to install a Theft Deterrent Ignition Cylinder Protector on certain 2010-2022MY…
- PITSTOP
TECHNICAL OPERATIONS: EXTERNAL DAMAGE TO ULTRASONIC SENSOR: This Pitstop provides information related to Parking Distance Warning (PDW) alerts and repairs involving ultrasonic sensors. The PDW system alerts the driver…
- TECHNICAL SERVICE BULLETIN
VOLUNTARY EMISSIONS SERVICE CAMPAIGN: THETA II 2.4L GDI EMISSIONS ECM LOGIC IMPROVEMENT (SC340) - This bulletin has been revised to include additional information. New/revised sections of this bulletin are indicated by…
- VOLUNTARY EMISSIONS SERVICE CAMPAIGN
OWNER NOTIFICATION (SC340 FLIGHT 102 / JF) - 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…
- VOLUNTARY EMISSIONS SERVICE CAMPAIGN
OWNER NOTIFICATION (SC340 FLIGHT 101 / JF) - 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…
- TECHNICAL SERVICE BULLETIN
VOLUNTARY EMISSIONS SERVICE CAMPAIGN: THETA II 2.4L GDI EMISSIONS ECM LOGIC IMPROVEMENT (SC340) - This bulletin provides information to upgrade the Electronic Control Module ‘ECM’ system software for certain…
NHTSA lists 118 bulletins for this year; the 12 newest are shown here.
Other years of this model
Questions and answers
What are the most common problems with the 2018 KIA Optima?
Owner complaints to NHTSA most often mention: engine, electrical system, powertrain. Total complaints: 233. The most frequent symptoms in complaint texts: warning lights, check engine (23%), oil leak or consumption (22%), smoke, burning smell, fire (12%).
How many service bulletins (TSB) were issued for the 2018 KIA Optima?
NHTSA lists 118 manufacturer service bulletins for this year. A bulletin tells dealers how to diagnose or fix a known issue; it is not a recall.
Should I buy a 2018 KIA Optima from a US auction?
Owner complaints describe defects, not crash damage. Before bidding, check the components listed above and review the lot photos: VinWind builds a report of visible and hidden damage by VIN.
Other 2018 models
Read also
Sources: public NHTSA data (USA): service bulletins and owner complaints; YouTube: links to videos credited to their authors. Complaints are owner statements not verified by NHTSA, and describe defects rather than crash damage. Data updated 2026-11-04.