P0306 on Honda: How to Diagnose & Fix
Cylinder 6 Misfire Detected
4 Honda models · 9 documented issues · 7 critical · $81-$8,000 repair
P0306 on Honda by model: symptoms, diagnosis and fix
Variable Cylinder Management (VCM) causes excessive oil consumption (1 quart every 1,000-1,500 miles), engine misfires, and fouled spark plugs. The reciprocating effect creates vacuum that pulls oil past piston rings. Leads to premature failure of spark plugs, catalytic converters, engine mounts, and cylinder walls. 2013 class action lawsuit identified 1.6 million affected vehicles.
Common Symptoms
- Excessive oil consumption (1 qt per 1,000-1,500 miles)
- Engine misfires (P0300-P0306 codes)
- Fouled spark plugs
- Rough idle or hesitation
- Check engine light
- Excessive engine vibration when VCM activates
- Blue smoke from exhaust
How to Fix
Disable VCM using aftermarket devices: VCMuzzler II ($81), VCMTuner II ($150-200), or S-VCM Controller ($180-250). Check oil level every 500-1,000 miles and top off as needed. Use synthetic 0W-20 oil. Replace spark plugs every 30k-50k miles instead of 100k. Severe cases may need engine rebuild ($4,000-$8,000).
Owner tips & cautions
- TipDisabling VCM reduces damage to engine mounts ($800) and minimizes transmission torque converter wear
- TipCheck oil level every 500-1,000 miles and keep 2-3 quarts of oil in vehicle for top-offs
- WarningDo not ignore excessive oil consumption - running engine low on oil can cause catastrophic engine failure
Sources for this issue (1)
2016-2018 Pilots suffer from debris in direct-injection fuel system causing internal wear or clogging inside injectors. Causes misfire codes (P0300-P0306), catalyst efficiency codes (P219A/B, P0420/P0430), rough idle, and stalling. TSB 20-100 addresses this defect. Honda extended warranty to 10 years/150,000 miles for 2016-2017 models.
Common Symptoms
- Check engine light with misfire codes (P0300-P0306)
- Catalyst efficiency codes (P0420, P0430, P219A, P219B)
- Rough idle or engine stumbling
- Engine stalling at stops
- Poor fuel economy
- Fuel smell at idle
- Loss of power under acceleration
How to Fix
Visit Honda dealer for diagnosis using TSB 20-100. For vehicles with these codes, Honda will replace fuel injectors and catalytic converters under extended warranty (10 years/150,000 miles for 2016-2017). PCM software update also available. Keep documentation of all misfires and check engine lights to support warranty claim.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Genuine Honda 16010-RLV-315 six-piece fuel-injector setOEMHonda 16010-RLV-315
Retail fallback only after Honda warranty/VIN review and diagnosis confirm the injector branch Fitment/availability: 2016-2018 U.S.
As an Amazon Associate, we earn from qualifying purchases; other part links may also earn au7o a commission. Confirm fitment by VIN before buying.
Owner tips & cautions
- TipHonda extended warranty to 10 years/150,000 miles for 2016-2017 models with these codes - document all issues
- TipIf dealer denies warranty claim, reference TSB 20-100 specifically and escalate to Honda corporate
- WarningDo not ignore misfire codes - continued driving can damage catalytic converters ($1,500-$3,500 to replace)
- WarningThese codes often misdiagnosed as VCM issues - verify with dealer using TSB 20-100 for correct diagnosis
Sources for this issue (2)
On the J35 V6, the rubber valve cover gaskets and the integrated spark plug tube seals harden and shrink with age and heat, allowing oil to weep onto the hot exhaust manifolds (burning-oil smell) and, more seriously, to pool down inside the spark plug wells. Oil saturates the ignition coil boots and shorts the spark, producing misfires and a Check Engine Light. The rear (firewall-side) bank is hardest to access, so the leak is often neglected until misfires appear.
Common Symptoms
- Burning oil smell from the engine bay
- Oily residue/grime on top of the valve covers
- Oil pooled in the spark plug wells
- Rough idle, misfire, and Check Engine Light
- Occasional blue smoke / slightly higher oil consumption
How to Fix
Replace both valve cover gaskets and the spark plug tube seals (gasket sets include the tube seals); clean oil from the spark plug wells and inspect/replace any oil-soaked ignition coil boots and fouled spark plugs. Parts are inexpensive ($40-$80 per set) but labor is significant on the rear bank.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Fel-Pro VS50773R complete valve-cover gasket setOEMFel-Pro VS50773R / PartsGeek 29982-05418108
Confirm package contents on arrival.
- Genuine Honda 12030-5G0-000 front head-cover gasket packageOEMHonda 12030-5G0-000
2016-2020 front/radiator-bank gasket and tube-seal branch Fitment/availability: 2016-2020 U.S. Honda Pilot 3.5L V6 front head cover; package includes the front cover gasket, tube seals and sealing washers.
- Genuine Honda 12050-5G0-000 rear head-cover gasket packageOEMHonda 12050-5G0-000
2016-2020 rear/firewall-bank gasket and tube-seal branch Fitment/availability: 2016-2020 U.S. Honda Pilot 3.5L V6 rear head cover; package includes the rear cover gasket, tube seals and screw grommets.
As an Amazon Associate, we earn from qualifying purchases; other part links may also earn au7o a commission. Confirm fitment by VIN before buying.
Sources for this issue (2)
The 8th generation Accord V6 (3.5L J35Z2) with Variable Cylinder Management (VCM) deactivates 3 cylinders at highway speeds, causing excessive oil consumption (1 quart per 1,000-1,500 miles), misfires, and accelerated engine vibration that damages engine mounts. When VCM deactivates cylinders, insufficient ring pressure allows oil to bypass rings into combustion chamber. The class action lawsuit (Rodriguez v. American Honda, 2013) covered 1.87 million vehicles. Honda settled in 2016 providing extended warranty for engine repairs related to VCM-caused misfires and oil consumption. Many owners in the Drive Accord community disable VCM immediately upon purchase.
Common Symptoms
- Oil level dropping 1-2 quarts between 3,000-5,000 mile oil changes
- Engine misfires (P0300-P0306 codes)
- Fouled spark plugs with carbon and oil deposits
- Excessive vibration felt through steering wheel and seats
- Check engine light with misfire and/or catalyst codes
- Catalytic converter efficiency codes (P0420, P0430)
- Blue smoke from exhaust at startup
How to Fix
Install VCM disabler device: VCMuzzler II (~$81, simplest install, no power wire), VCMTuner II ($150-200, more features), or S-VCM Controller ($180-250, automatic temperature adjustment). Check oil every 500-1,000 miles until VCM disabled. Replace fouled spark plugs with NGK DILKAR7B11 ($5-8 each) every 30,000-50,000 miles. Honda 2016 class action settlement may provide extended warranty for misfires/consumption - contact Honda with VIN. Severe cases (catalytic converters destroyed): $2,000-3,500 replacement.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- VCMuzzler II VCM suppression deviceOEMVCMuzzler II
Optional owner-selected VCM suppression after understanding the device's operating tradeoffs Fitment/availability: 2008-2012 Accord V6 automatic only; vendor explicitly excludes manual-transmission Accord. Select model year, model and pi…
- S-VCM ControllerOEMS-VCM Controller
Confirm connector/application with vendor.
As an Amazon Associate, we earn from qualifying purchases; other part links may also earn au7o a commission. Confirm fitment by VIN before buying.
Sources for this issue (1)
Variable Cylinder Management (VCM) deactivates 3 cylinders during light-load driving to improve fuel economy. When inactive cylinders reactivate, vacuum pulls oil past piston rings into the combustion chamber, causing excessive oil consumption (1 quart per 1,000-1,500 miles vs. normal 1 quart per 3,000-5,000). Oil burning causes spark plug fouling, misfires, rough idle, and accelerated catalytic converter wear. 2013 class action lawsuit identified 1.6 million affected Honda vehicles including 2006-2013 Ridgelines.
Common Symptoms
- Excessive oil consumption (1 quart per 1,000-1,500 miles)
- Engine misfire codes P0300-P0306
- Fouled spark plugs with carbon buildup and wet deposits
- Rough idle or hesitation
- Check engine light illuminated
- Blue or gray smoke from exhaust
- Excessive engine vibration when VCM activates
How to Fix
Disable VCM using aftermarket devices: VCMuzzler II ($81), VCMTuner II ($150-$200), or S-VCM Controller ($180-$250). Check oil level every 500-1,000 miles until VCM disabled. Use synthetic 0W-20 oil. Replace spark plugs every 30,000-50,000 miles instead of 100,000. Severe engine damage may require rebuild ($4,000-$8,000).
Owner tips & cautions
- TipMonitor oil level obsessively and keep 2-3 quarts in vehicle for top-offs between oil changes
- WarningInstall VCM disabler as preventive measure, not reactive - engine damage from oil consumption is permanent and expensive
- TipReplace spark plugs every 30k-50k miles instead of 100k - fouled plugs cause misfires that damage catalytic converters ($1,500-$3,500)
- TipDisabling VCM also protects engine mounts and transmission from excessive wear and vibration
Sources for this issue (3)
The 3.5L aluminum engine with steel spark plugs experiences thermal stress due to temperature differences. Spark plugs back out (loosen) due to aluminum block expansion/contraction cycles, causing misfires and potentially breaking inside the combustion chamber. Loose spark plugs allow coil packs to melt and enter the engine block causing catastrophic damage. After 60,000 miles, Honda service bulletins specify spark plug torque should be double-checked. Affects all J35 engine platforms (Pilot, Odyssey, Ridgeline).
Common Symptoms
- Misfire codes P0300-P0306
- Check engine light
- Rough idle or hesitation
- Coil pack melting or burning visible in cylinder
- Complete engine failure if melted coil enters combustion chamber
- Engine won't start (broken/loose plugs)
How to Fix
At 60,000 miles: remove spark plugs and re-torque to proper spec (18 ft-lbs) using torque wrench. Inspect each plug for backing out or looseness. Use OEM Honda spark plugs only. Coil pack replacement if melted: $150-$300 per coil + labor. Engine head repair if melted coil damaged head: $1,500-$3,000+. Full engine rebuild if catastrophic: $4,000-$8,000+.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Genuine Honda / NGK 9807B-5517W IZFR5K11 spark plug, quantity oneOEMHonda 9807B-5517W / NGK IZFR5K11
exact early spark-plug replacement after inspection confirms plug replacement is due or required Fitment/availability: 2006-2008 U.S.
- Genuine Honda / NGK 12290-R70-A01 ILZKR7B11 spark plug, quantity oneOEMHonda 12290-R70-A01 / NGK ILZKR7B11
exact later spark-plug replacement after inspection confirms plug replacement is due or required Fitment/availability: 2009-2010 U.S.
As an Amazon Associate, we earn from qualifying purchases; other part links may also earn au7o a commission. Confirm fitment by VIN before buying.
Owner tips & cautions
- TipUse torque wrench when installing spark plugs - do not over-tighten (18 ft-lbs spec exactly)
- TipAlways work on engine when completely cool - aluminum expands significantly when hot and causes incorrect torque readings
- TipCheck spark plug torque at 60,000 miles and every 30,000 miles thereafter as preventive maintenance
- WarningHave coil packs inspected immediately if misfire codes appear - replacing coils early prevents catastrophic $4,000+ engine damage
Sources for this issue (2)
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 Honda?
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 Honda it is documented across 4 models: Pilot, Accord, Ridgeline, Passport.
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 Honda?
Published repair estimates on Honda range from $81 to $8,000 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.