P0174 on Honda: How to Diagnose & Fix
System Too Lean (Bank 2)
3 Honda models · 3 documented issues · 3 critical · $81-$3,500 repair
P0174 on Honda by model: symptoms, diagnosis and fix
Variable Cylinder Management (VCM) deactivates 3 rear cylinders during light load, but insufficient pressure allows oil to bypass the piston rings into the combustion chamber. Causes excessive oil consumption (1 quart per 1,000 miles), fouled spark plugs, catalytic converter damage, and premature piston ring wear. Honda settled a class-action lawsuit over the problem.
Common Symptoms
- Excessive oil consumption (1 qt per 1,000 miles or more)
- Engine misfire codes (P0300-P0304, typically cylinders 1-4)
- Fouled/oil-soaked spark plugs
- Rough idle and vibration
- Check engine light (misfire and catalyst codes)
- White smoke from exhaust on startup
- Failed catalytic converters (P0420/P0430)
How to Fix
Install VCM disable device (VCMuzzler, VCMTuner) which prevents cylinder deactivation and stops oil consumption. Replace fouled spark plugs after installing disabler. Honda settled a class action (Soto v. American Honda) covering 2008-2013 Odyssey with an 8-year warranty extension for engine misfire repairs, and announced a further warranty extension in June 2025 for certain 2013-2017 Odyssey. Severe cases may require piston ring replacement ($3,000-$5,000). 2014-2017 models still use VCM.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Genuine Honda/NGK 9807B-5517W IZFR5K11 spark plug, eachOEMHonda 9807B-5517W / NGK IZFR5K11
Early-generation plug branch only after inspection identifies a fouled plug and exact catalog application Fitment/availability: 2005-2007 U.S. Honda Odyssey 3.5L applications in this issue; Honda catalogs 9807B-5517W across 2005-2010 but…
- Genuine Honda/NGK 12290-R70-A01 ILZKR7B11 spark plug, eachOEMHonda 12290-R70-A01 / NGK ILZKR7B11
VCM plug-fouling branch after code and plug inspection identifies replacement Fitment/availability: 2008-2010 U.S. Honda Odyssey EX-L/Touring with VCM; select 12290-R70-A01.
- Genuine Honda/NGK 12290-R71-L01 DILZKR7A11G spark plug, eachOEMHonda 12290-R71-L01 / NGK DILZKR7A11G
Fourth-generation plug-fouling branch after P0301-P0304 and physical plug diagnosis Fitment/availability: 2011-2017 U.S. Honda Odyssey all trims; sold individually and six are required for a full set.
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Owner tips & cautions
- TipCheck oil level every fuel fill-up on VCM-equipped models - carry a quart of oil in the van
- WarningDon't ignore misfire codes - prolonged misfires destroy catalytic converters ($2,000+ repair)
Sources for this issue (2)
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. The 2013 VCM class-action settlement (8-year warranty extension) covered only 2009-2013 Pilots, not these model years.
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 (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 (Soto v. American Honda, filed 2012) covered about 1.6 million VCM vehicles. Honda settled in 2013, providing an 8-year, unlimited-mileage extended warranty for repairs related to VCM-caused misfires and spark plug fouling. Many owners in the Drive Accord community disable VCM immediately upon purchase.
Common Symptoms
- Oil level dropping about 1 quart every 1,000-1,500 miles
- 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's 2013 class action settlement provided an 8-year extended warranty for misfires with fouled plugs - contact Honda with VIN (the 8-year term has now run out on most cars). 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 (2)
P0174 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 P0174 mean on a Honda?
P0174 stands for "System Too Lean (Bank 2)." P0174 means the engine computer detected that the air-fuel mixture on Bank 2 (the side of the engine that does not contain cylinder 1) is running too lean — too much air relative to fuel. The computer monitors this through the oxygen/air-fuel sensors and fuel trims; when it has to add a large amount of extra fuel to compensate and still can't reach the target, it flags the mixture as too lean. A lean condition can cause rough idle, hesitation, or misfires, and over time can raise combustion temperatures. Because it's Bank 2 specific, an unmetered air leak on that bank or a fuel delivery shortfall is typical. On Honda it is documented across 3 models: Odyssey, Pilot, Accord.
What are the most common causes of P0174?
The most common causes of P0174 are: Vacuum or intake air leak (hoses, gaskets, PCV), Dirty or failing mass airflow (MAF) sensor, Weak fuel pump or restricted fuel filter (low fuel pressure), Clogged or underperforming fuel injectors, Leaking intake manifold or throttle body gasket, Faulty or contaminated oxygen / air-fuel sensor, Exhaust leak upstream of the oxygen sensor, Stuck-open EGR valve. The specific cause varies by vehicle.
How much does it cost to fix P0174 on a Honda?
Published repair estimates on Honda range from $81 to $3,500 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.
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Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.