P0306 on Kia: How to Diagnose & Fix
Cylinder 6 Misfire Detected
1 Kia model · 1 documented issue · $400-$800 repair
P0306 on Kia by model: symptoms, diagnosis and fix
All turbocharged GDI engines in the Stinger (3.3T, 2.5T, 2.0T) develop carbon deposits on the intake valves over time because GDI fuel injection sprays fuel directly into the combustion chamber rather than onto the valve stems. Without port injection washing the valves, carbon accumulates and restricts airflow, causing rough idle, misfires, and power loss. This typically becomes noticeable between 40,000-80,000 miles.
Common Symptoms
- Rough idle that worsens over time
- Hesitation during acceleration
- Misfires and check engine light (P0300-P0306)
- Decreased fuel economy
- Loss of power compared to when new
How to Fix
Walnut shell blasting of intake valves is the most effective treatment ($400-700 at a shop). CRC GDI IVD Intake Valve Cleaner (#05319) can slow buildup between cleanings. Some owners use catch cans (Mishimoto part #MMBCC-KS-18 for Stinger) to reduce oil vapor reaching the intake. Preventive walnut blasting every 40,000-50,000 miles is recommended.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- CRC 05319 GDI IVD intake-valve and turbo cleanerOEMCRC 05319
Optional light-deposit treatment or maintenance between professionally diagnosed cleanings Fitment/availability: Gasoline direct-injection Stinger engines only when the product can be introduced exactly according to CRC instructions; not…
- Mishimoto MMBCC-STNGR-18PBE PCV-side baffled oil catch canOEMMishimoto MMBCC-STNGR-18PBE
Optional preventive oil-vapor separator after existing deposits are addressed Fitment/availability: 2018-2021 Kia Stinger GT with Lambda II 3.3L twin-turbo only; not the 2.0T, 2.5T or unvalidated 2022-2023 branches. Inspect/empty initial…
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P0306 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0306 mean on a Kia?
P0306 stands for "Cylinder 6 Misfire Detected." This code means the engine computer detected a misfire on cylinder 6 — that cylinder isn't burning its fuel-air mixture properly. The computer senses misfires by watching for tiny variations in crankshaft speed each time a cylinder should fire, and when cylinder 6 repeatedly fails to contribute, this code sets. You may feel a shake or stumble, especially at idle or under load, along with reduced power and possibly a flashing check-engine light, which signals a misfire severe enough to damage the catalytic converter. A misfire comes down to a problem with spark, fuel, or compression in that cylinder. On Kia it is documented across 1 model: Stinger.
What are the most common causes of P0306?
The most common causes of P0306 are: Worn or fouled spark plug on cylinder 6, Failed ignition coil for cylinder 6, Clogged, leaking, or failed fuel injector, Vacuum or intake air leak affecting that cylinder, Low compression (worn rings, burnt valve, head gasket), Damaged plug wire or coil connector, Carbon buildup or worn valvetrain components. The specific cause varies by vehicle.
How much does it cost to fix P0306 on a Kia?
Published repair estimates on Kia range from $400 to $800 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
Looking for P0306 on a different make?
View P0306 across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.