P0306: Cylinder 6 Misfire Detected
73 vehicles · 24 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 2009-2019 Porsche 911 (Carrera, Carrera S, Carrera 4, Carrera 4S, GTS, GT3), plus 70 other vehicles, with repair costs ranging from $50 to $25,000.
Common Causes
Typical Repair Cost
Based on 91 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 (73)
Cylinder Misfire Diagnosis and Ignition-Coil Failure — 2.7T APB/BEL
Fuel-Quality or Deposit-Related Rough Running and Misfire Diagnosis
2009-2025 Q5 Gasoline-Quality Deposit Diagnosis - TSB 2014753/13
2019-2021 A6 3.0L Misfire Codes - Check ECM Software Before Mechanical Cleaning
2007-2008 RS4 Deposit-Related Cold-Start Misfire - Diagnose Before Cleaning
Valve Cover Gasket Oil Leak
Intake Valve Carbon Buildup
S58 Intake Valve Carbon Buildup
S58 Intake Valve Carbon Buildup
S63/S63TU Ignition Coil Premature Failure
N54 High Pressure Fuel Pump (HPFP) Failure - E89 Z4 sDrive35i/35is
Direct Fuel Injector Failure (S55)
Valve Cover Gasket Oil Leak (M52/M54 6-Cylinder)
S55 High-Pressure Fuel Injector Failure - F82/F83 M4
5.3L Vortec AFM Active Fuel Management Oil Consumption and Lifter Failure
4.3L Vortec CSFI "Spider" Injector Poppet Valve Leaking/Clogging
5.3L V8 Active Fuel Management (AFM) Lifter Collapse and Camshaft Damage
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 5.7L MDS Lifter and Camshaft Failure
Pentastar Cylinder Head Failure
5.7L HEMI MDS Lifter Tick and Camshaft Failure
3.6L Pentastar Valvetrain Failure (Rocker Arm / Lifter Ticking, Misfire, Engine Damage)
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)
Valve Spring Failure on 6.4L 392 HEMI (High-RPM and Modified/Boosted Cars)
Random Misfire / Rough Idle (P0300) From Worn Spark Plugs & Failing Ignition Coils
3.6L Pentastar V6 Left Cylinder Head Failure (Misfire on Cylinders 2/4/6)
1.5L EcoBoost 3-Cylinder Coolant Loss and Engine Failure
3.5L EcoBoost Intercooler Condensation Causing Shudder and Limp Mode
2.7L EcoBoost Coolant Intrusion from Cracked Cylinder Head
3.5L EcoBoost (Gen 1) Intake Valve Carbon Buildup — Misfire, Rough Idle, Power Loss
4.6L 2-Valve Triton V8 Spark Plug Ejection / Stripped Head Threads (TSB 07-21-2)
4.0L SOHC / OHV Waste-Spark Coil Pack Misfire (P0300 Series)
Ignition Coil Pack Failure
3.5L EcoBoost Ignition Coil and Spark Plug Misfire (Often Caused by Broken Exhaust Manifold Studs)
5.4L 2-Valve Spark Plug Blow-Out From Cylinder Head
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 Leak Causing Misfires
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
HEMI Engine Tick/Lifter Noise
2011-2013 3.6L Left-Head Misfire - Follow the X56 Leak-Down Test
3.6L Pentastar Rocker Arm / Lifter Needle-Bearing Failure — Valvetrain Tick, Misfire & Cam Damage
3.6L Pentastar V6 left cylinder head failure / engine tick (early build)
Early 3.6L Pentastar Left Cylinder Head Valve Seat/Guide Wear Causing Misfires (Warranty Extension X56 / TSB 09-002-14)
2018-2022 WK / 2021-2025 WL 3.6L Intake Camshaft and Rocker Wear
Ignition Coil Rail Failure Causing Misfire on 4.0L
Navigator 5.4L 3V Triton Spark Plug Breakage on Removal
Coil-on-Plug Ignition Coil Failure and Misfires (4.6L V8)
2.7L EcoBoost Excessive Oil Consumption from Faulty Valve Guides
HEMI Lifter/Camshaft Failure
MDS Lifter Failure and Hemi Tick (5.7L)
6.4L HEMI Valvetrain Failure (Roller Lifter/Camshaft Wear, "HEMI Tick")
5.7L HEMI MDS Lifter Failure
3.0L Hurricane Twin-Turbo I6 Random Misfire (P0300) on Early-Build Trucks Needing ECU/Ignition Reflash
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 73 vehicle models from 24 manufacturers: Acura, Audi, BMW, Chevrolet, Chrysler, Dodge, Ford, GMC, Genesis, Honda, Hyundai, Jaguar, Jeep, Lexus, Lincoln, Mazda, Nissan, Porsche, RAM, Ram, Saturn, Subaru, Toyota, Volkswagen.
Sources (12)
- RecallNHTSA Recall 17V-224
- 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
- RecallNHTSA Recall 19V-601 - Engine Bearing Failure
- 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.