Trouble codes › Known problems › Honda 3.5L V6 VCM misfires and fouled spark plugs
Honda 3.5L V6 VCM misfires and fouled spark plugs
Codes: P0300, P0301, P0302, P0303, P0304, P0305, P0306
On Honda V6s with Variable Cylinder Management (Accord, Odyssey, Pilot and Crosstour), misfires (P0301-P0306) from oil-fouled spark plugs are well documented; Honda traced it to piston rings, extended warranty coverage and settled a class action for 2008-2013 vehicles.
A steady light with a mild misfire is usually drivable short term. If the check-engine light flashes, drive as little as possible to protect the catalytic converters, and get it checked soon.
Which vehicles
- Honda Accord (V6) 2008-2017
- Honda Odyssey 2008-2017
- Honda Pilot 2009-2015
- Honda Crosstour 2010-2015
Why it happens
VCM shuts off some cylinders (often the rear bank) at cruise to save fuel. On many of these engines, oil gets past the piston rings on those cylinders and fouls the spark plugs, causing misfires; Honda's bulletins describe piston rings that can rotate and line up their gaps.
It also comes with oil consumption, and some owners report vibration from the engine mounts when VCM switches on and off.
Symptoms
- Misfire codes, most often on one or two cylinders
- Oil consumption between changes
- Rough running or vibration at cruise
How to confirm it
- Pull the spark plugs from the misfiring cylinders: oil fouling points to the ring problem.
- Check oil consumption; Honda dealers may run an oil consumption test before covering repairs.
- Swap coils to rule out a bad coil.
- Ask a Honda dealer to check your VIN for warranty extensions and bulletins.
The repair
- Honda's repair for covered vehicles replaced the piston rings (and related parts) on affected cylinders.
- Short term, new spark plugs stop the misfire but it usually returns while the rings are bad.
- Some owners use aftermarket devices to disable VCM; that's an owner's choice and may affect warranty.
Recalls, bulletins and warranty programs
- Honda warranty extension (Soto v. American Honda settlement, 2013)
- For about 1.6 million V6 VCM vehicles including 2008-2012 Accord, 2008-2013 Odyssey, 2009-2013 Pilot and Crosstour: misfire repairs for P0301-P0304 covered to 8 years with unlimited mileage from the original purchase, with reimbursement for paid repairs. Coverage periods for many vehicles have now ended.
- Later extension (2025)
- Honda announced another warranty extension for certain 2013-2015 Pilot and 2013-2017 Odyssey vehicles; ask a dealer with your VIN for the details.
Programs can expire or depend on your VIN. Check nhtsa.gov/recalls and ask a dealer to run your VIN for open recalls, bulletins and extended coverage.
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Researched October 2026 from service bulletins, recall records and repair-industry reporting. Your vehicle may differ; confirm with your service information and a dealer before paying for major repairs.