P0306: Cylinder 6 Misfire Detected
76 vehicles · 22 makes · $50-$25,000 repair
Most Reported On
P0306 is an OBD-II diagnostic trouble code meaning “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. This code is most commonly reported on 2011-2019 Hyundai Sonata (Base, GL, GLS, LX, Limited, SE, SEL, SEL Plus, Sport), 1999-2005 Mazda MX-5 Miata, and 2011-2019 Hyundai Tucson (GLS, Limited, SEL, Sport, Ultimate, Value), plus 73 other vehicles, with repair costs ranging from $50 to $25,000.
Common Causes
Typical Repair Cost
Based on 89 documented vehicle-specific issues. Actual cost depends on root cause and vehicle.
Diagnostic Tools
To diagnose P0306, you'll need an OBD-II scanner. Here are our recommendations at every price point.
ANCEL AD310 Classic OBD-II Scanner
by ANCEL
A simple, affordable code reader that reads and clears check engine codes. Great for quick diagnostics on any OBD-II vehicle (1996+).
- Read & clear engine codes
- View freeze frame data
- I/M readiness status
- No batteries or app needed
BlueDriver Pro Bluetooth Scanner
by BlueDriver
Bluetooth OBD-II scanner with a free companion app. Provides enhanced diagnostics, smog readiness, and repair reports sourced from a database of verified fixes.
- Enhanced diagnostics (ABS, SRS, transmission)
- Repair Reports with verified fixes
- Smog check readiness
- Free app (iOS & Android)
LAUNCH CRP123X OBD-II Scanner
by LAUNCH
A professional-grade handheld scanner that reads all four major systems (engine, transmission, ABS, SRS) with live data streaming and graphing.
- Engine, transmission, ABS, SRS diagnostics
- Live data stream & graphing
- AutoVIN for vehicle identification
- Free lifetime updates via Wi-Fi
Autel MaxiCOM MK808S Diagnostic Tool
by Autel
Shop-level diagnostic tablet with bi-directional control, active tests, and full system coverage. Ideal for serious DIYers and small shops.
- All-system diagnostics (25+ modules)
- Bi-directional control & active tests
- Oil reset, EPB, BMS, TPMS, injector coding
- 7-inch touchscreen with Android OS
As an Amazon Associate, we earn from qualifying purchases. Prices are approximate and may vary.
Vehicles Affected (76)
4.0T Direct Injection Carbon Buildup
4.0T Carbon Deposit Accumulation
3.0T Intake Valve Carbon Buildup
2.5T Five-Cylinder Carbon Buildup
Direct Injection Carbon Buildup
Severe Carbon Buildup on Intake Valves
Carbon Buildup on Intake Valves (4.2 V8 FSI and 5.2 V10 FSI)
Severe Carbon Buildup on Intake Valves (2.5T 5-Cylinder)
Severe Carbon Buildup on Intake Valves (Direct Injection)
4.0T Carbon Buildup on Intake Valves
Carbon Buildup on Intake Valves (Direct Injection)
Carbon Buildup on Intake Valves (4.0T Twin-Turbo V8)
Intake Valve Carbon Buildup (Direct Injection)
2.7T Ignition Coil Pack Failure Causing Misfires and Flashing Check Engine Light
Severe Carbon Buildup on Intake Valves (Direct Injection)
4.2L V8 Carbon Buildup on Intake Valves
4.2L V8 Carbon Buildup and High-Rev Issues
Severe Carbon Buildup on Intake Valves (4.0T V8)
Turbo Wastegate Rattle and Carbon Buildup
Direct Injection Carbon Buildup on Intake Valves
Severe Carbon Buildup Causing Valve Damage (3.0T TFSI)
Severe Carbon Buildup on Intake Valves (3.0T)
Intake Valve Carbon Buildup
High-Pressure Fuel Injector Issues
Valve Cover Gasket Oil Leak
Intake Valve Carbon Buildup
S58 Intake Valve Carbon Buildup
S58 Intake Valve Carbon Buildup
N54 High-Pressure Fuel Pump (HPFP) Failure (135i / 1M)
S55 High-Pressure Fuel Injector Failure - F82/F83 M4
S63/S63TU Ignition Coil Premature Failure
N54 High Pressure Fuel Pump (HPFP) Failure - E89 Z4 sDrive35i/35is
N54 Spark Plug & Ignition Coil Failure (135i / 1M)
Ignition Coil Pack Failure Causing Misfires and Check Engine Light on M52TU/M54 Engines
Direct Fuel Injector Failure (S55)
5.3L Vortec AFM Active Fuel Management Oil Consumption and Lifter Failure
AFM/DFM Lifter Failure (5.3L/6.2L V8)
Injector Wiring Harness Chafing (Duramax)
5.3L V8 (AFM/DFM) collapsed/failed lifter causing ticking and cylinder misfire
L99 AFM Lifter Failure and Camshaft Damage on 6.2L Automatic Cars
HEMI MDS Lifter Tick
HEMI MDS Lifter Tick
Pentastar V6 Rocker Arm/Lifter Tick
HEMI Lifter/MDS Tick
Pentastar V6 Rocker Arm/Lifter Tick
Rod Bearing Failure from Oil Starvation (Track Use)
3.6L Pentastar V6 Left Cylinder Head Failure (Misfire on Cylinders 2/4/6)
1.5L EcoBoost 3-Cylinder Coolant Loss and Engine Failure
5.4L 2-Valve Spark Plug Blow-Out From Cylinder Head
Ignition Coil Pack Failure
4.6L 2-Valve Spark Plug Ejection/Breakage
Fuel Injector Debris Causing Misfires and Catalyst Codes
Spark Plugs Backing Out - Coil Pack Melting and Engine Damage
Valve Cover Gasket and Spark Plug Tube Seal Oil Leaks Causing Misfires
Timing Belt and Water Pump Neglect Leading to 3.2L V6 Engine Damage
2.7L EcoBoost Excessive Oil Consumption from Faulty Valve Guides
Navigator 5.4L 3V Triton Spark Plug Breakage on Removal
Coil-on-Plug Ignition Coil Failure and Misfires (4.6L V8)
FAQ
What does P0306 mean?
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.
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?
Repair costs for P0306 range from $50 to $25,000, depending on the vehicle and root cause.
Which vehicles are affected by P0306?
Au7o has documented P0306 across 76 vehicle models from 22 manufacturers: Acura, Audi, BMW, Cadillac, Chevrolet, Chrysler, Dodge, Ford, GMC, Honda, Hyundai, Jeep, Lexus, Lincoln, Mazda, Nissan, Porsche, RAM, Saturn, Subaru, Toyota, Volkswagen.
Sources (12)
- RecallNHTSA Recall 17V-224
- RecallNHTSA Recall 19V-601 - Engine Bearing Failure
- manufacturerLN Engineering: What is Porsche Cylinder Bore Scoring
- manufacturerLN Engineering: Identifying the Porsche Bore Scoring Problem
- mediaThe Drive: The Complete History and Current State of the Porsche Bore Scoring Issue
- manufacturerPorsche Club of America: Bore scoring and how to prevent it
- manufacturerFlat 6 Innovations: Cylinder Bore Scoring
- ForumRamForumz: Cam / lifter failure class action
- ForumRamForumz: Ram hemi cam/lifter failure thread
- otherCarComplaints: 2011 Dodge Ram 1500 Lifter And Cam Issue
- ForumRamForumz: Cam / lifter failure class action page 4
- ForumRamForumz: Ram hemi cam/lifter failure thread page 8
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.