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Kia Optima — what actually breaks, by engine

2015–2020 · 1,550 federal complaints · 5 engines

Reliability ratings usually stop at the model. But two Optimas with different engines can fail in completely different ways — and the engine is a choice you make at purchase. Here is what owners actually complained about, separated by engine.

Kia Optima
Photo: Charles from Port Chester, New York · CC BY 2.0

Ownership profile

Each axis is this model's percentile within its own segment — comparing a pickup's fuel economy against a compact car's would say nothing. Built from EPA test data.

Fuel economy75Running cost71Low emissions76Cabin space90Cargo space85Displacement25
29 MPG Fuel economy$2,100/yr Running cost309 g/mi Low emissions105 cu ft Cabin space16 cu ft Cargo space2.0 L Displacement

Value for money

90/ 100

$22,400

Capability per relative dollar, ranked against the same segment. It divides this model's average percentile across the axes above by its price relative to the segment median — so 80 means it delivers more per dollar than 80% of its class.

Price source: CarAPI vehicle trim database — base-trim MSRP, median across 2015-2020 model years. Unlike every other figure on this page, the price does not come from a federal record. It is the manufacturer's list price for the cheapest trim — what people actually paid varies with incentives and options, so treat this one axis as indicative, not exact.

What each engine's complaints are about

Share of component mentions. One complaint can name several components, so these describe what an engine's complaints are about — they are not a failure rate.

Transmission & drivetrainEngineBrakesElectricalSteeringBody & structureFuel systemEverything else

GDI · 2.4L I4

2017–2020 · Naturally aspirated

675complaints
Engine 41%
Show the numbers
ComponentShareMentions
Transmission & drivetrain5.5%54
Engine41.4%406
Brakes4.5%44
Electrical8.2%80
Steering2.7%26
Body & structure2.3%23
Fuel system4.2%41
Everything else31.2%306

THETA II · 2.4L I4

2015–2016 · Naturally aspirated

596complaints
Engine 40%Electrical 9%
Show the numbers
ComponentShareMentions
Transmission & drivetrain5.4%46
Engine39.7%338
Brakes1.6%14
Electrical9.4%80
Steering2.7%23
Body & structure3.6%31
Fuel system4.8%41
Everything else32.7%278

T-GDI · 2.0L I4

2017–2020 · Turbo

149complaints
Engine 33%Electrical 11%
Show the numbers
ComponentShareMentions
Transmission & drivetrain7.1%16
Engine33.2%75
Brakes4.4%10
Electrical11.1%25
Steering2.2%5
Body & structure0.9%2
Fuel system5.3%12
Everything else35.8%81

THETA II · 2.0L I4

2016–2016 · Naturally aspirated

77complaints
Engine 31%
Show the numbers
ComponentShareMentions
Transmission & drivetrain5.0%6
Engine31.1%37
Brakes5.0%6
Electrical7.6%9
Steering1.7%2
Body & structure5.9%7
Fuel system5.9%7
Everything else37.8%45

T-GDI · 1.6L I4

2017–2020 · Turbo

53complaints
Transmission & drivetrain 18%Engine 24%
Show the numbers
ComponentShareMentions
Transmission & drivetrain17.9%14
Engine24.4%19
Brakes3.8%3
Electrical3.8%3
Steering2.6%2
Body & structure2.6%2
Fuel system7.7%6
Everything else37.2%29

Diagrams show cylinder layout and displacement from the decoded VIN data. Turbo and supercharger marks come from EPA certification records; where EPA cannot tell two engines of the same size apart, the mark is left off rather than guessed.

How many of those complaints involved a fire, crash or injury

Unlike the totals above, these can be compared between engines. Each figure is a share of that engine's own complaints, so how many were sold cancels out. The vertical mark is the average across every vehicle in this database.

GDI · 2.4L I4

675
Fire3.1%
Crash4.3%
Injury2.4%

THETA II · 2.4L I4

596
Fire2.7%
Crash3.9%
Injury2.7%

T-GDI · 2.0L I4

149
Fire4.7%+
Crash4.0%
Injury3.4%

all vehicles — Fire 1.1% · Crash 4.4% · Injury 2.6%

Still a share of complaints, not of vehicles on the road — it says how severe this engine's reported problems were, not how often it gets into trouble. Engines with fewer than 80 complaints are left out: fire is rare enough that a single extra case would swing the number.

Recalls on this model

Unlike everything above, recalls are issued for the whole model, not per engine — NHTSA publishes them by make, model and year. These are defects the manufacturer confirmed and filed federally, which makes them a useful counterweight to owner-reported complaints.

NHTSA told owners to park outside, away from buildings

The defect can start a fire even with the car parked and switched off.

  • Service Brakes, Hydraulic › Antilock/Traction Control/Electronic Limited Slip › Control Unit/Module — 2015–2015 23V652000
  • Service Brakes, Hydraulic › Antilock/Traction Control/Electronic Limited Slip › Control Unit/Module — 2015–2015 21V331000
  • Service Brakes, Hydraulic › Antilock/Traction Control/Electronic Limited Slip › Control Unit/Module — 2015–2015 20V519000

How this compares with what owners report →

10 recalls · covering 2015–2019

Service Brakes, Hydraulic 3Air Bags 2Latches/Locks/Linkages 1Forward Collision Avoidance 1Fuel System, Gasoline 1Hybrid Propulsion System 1Power Train 1
All recalls, with campaign numbers
YearsComponentNHTSA campaign
2015–2015Service Brakes, Hydraulic › Antilock/Traction Control/Electronic Limited Slip › Control Unit/Module23V652000
2015–2015Service Brakes, Hydraulic › Antilock/Traction Control/Electronic Limited Slip › Control Unit/Module21V331000
2015–2015Service Brakes, Hydraulic › Antilock/Traction Control/Electronic Limited Slip › Control Unit/Module20V519000
2016–2018Latches/Locks/Linkages › Trunk Lid › Latch23V594000
2019–2019Forward Collision Avoidance › Automatic Emergency Braking19V539000
2015–2017Fuel System, Gasoline › Delivery › Hoses, Lines/Piping, And Fittings18V907000
2017–2018Hybrid Propulsion System18V161000
2016–2016Air Bags › Frontal › Driver Side › Inflator Module17V007000
2016–2016Power Train › Axle Assembly › Axle Shaft16V705000
2016–2016Air Bags › Frontal16V231000

Recall repairs are free, always — any franchised dealer, regardless of the car's age, mileage, or how many owners it has had. A great many cars are driving around with recalls nobody ever redeemed.

More recalls does not mean a worse car. Recall counts rise with sales volume and model complexity, and a manufacturer that recalls promptly looks worse than one that drags its feet. Read what the recalls were for, not how many there were.

Check a specific car by VIN at NHTSA →

NHTSA crash-test ratings

Official 5-star ratings from standardized federal crash tests. Unlike the complaint figures above, these are directly comparable between models. Where a model year was tested in several versions, the lowest overall rating is shown.

Overall · 2020
★★★★★
Frontal · 2020
★★★★★
Side · 2020
★★★★★
Rollover · 2020
★★★★★

9.8% rollover risk

Model yearOverallFrontalSideRollover
2015★★★★★★★★★★★★★★★★★★★★
2016★★★★★★★★★★★★★★★★★★★★
2017★★★★★★★★★★★★★★★★★★★★
2018★★★★★★★★★★★★★★★★★★★★
2019★★★★★★★★★★★★★★★★★★★★
2020★★★★★★★★★★★★★★★★★★★★
Stability control: StandardForward-collision warning: StandardLane-departure warning: Standard

Source: NHTSA New Car Assessment Program.

Method, sources and limitations

How this was built

  1. Source: NHTSA public complaint database (api.nhtsa.gov), retrieved 2026-08-16. Every complaint carries the first 11 characters of the vehicle's VIN.
  2. Those partial VINs were decoded through NHTSA's vPIC service to identify the exact engine — 98.2% resolved successfully. This is how the data gets to engine level; model-level ratings cannot do this.
  3. Percentages are the share of component mentions, not of complaints. One complaint can name several components, so the figures describe what a given engine's complaints are about — they do not sum to a failure rate.

What this does not tell you

  • This is not a reliability ranking. Complaint totals track how many were sold, not how often they fail. Nobody publishes per-engine sales volume, so comparing totals between engines would be misleading. Read each engine's own breakdown; don't race them against each other.
  • Engines with fewer than 50 complaints are omitted — too small to say anything honest about.
  • Complaints are self-reported by owners. They skew toward problems that are alarming or expensive, and toward vehicles under active recall attention.

Compare with

Same segment, side by side — engines, running costs and what breaks.

Or see the whole segment at once: Midsize sedan →

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