P0430: How to Diagnose & Fix — Catalyst System Efficiency Below Threshold (Bank 2)
48 vehicles · 21 makes · $40-$10,000 repair
How to diagnose and fix P0430: most-reported vehicles
Ranked by owner reports. Each card gives the symptoms, how to confirm the cause, the fix, parts and sources for that vehicle.
Toyota Tundra · 2007–2019
Toyota Tundra V8 engines are prone to exhaust manifold cracking, particularly on the driver side where the air injection tube weld enters the manifold. Additionally, exhaust manifold bolts can corrode and break, causing exhaust leaks. The ticking noise is most noticeable at cold startup.
Common Symptoms
- Ticking noise at cold startup
- Exhaust smell in cabin
- Hissing sound from engine bay
- Reduced fuel economy
- Failed emissions test
How to Fix
Repair options include welding cracks (temporary), replacing with OEM manifolds ($800-$1,500), or upgrading to aftermarket headers ($1,000-$2,500). Broken bolts require extraction. Total repair costs range from $500 to $3,000+.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Toyota 17104-50220 genuine right exhaust manifold
replace a test-confirmed cracked or warped right 4.7L exhaust manifold Fitment/availability: Right-side 4.7L 2UZ-FE Tundra branch; use only after VIN, engine, production date, emissions and secondary-air configuration are confirmed Fitme…
- Toyota 17105-50210 genuine left exhaust manifold
replace a test-confirmed cracked or warped left 4.7L exhaust manifold Fitment/availability: Left-side 4.7L 2UZ-FE Tundra branch; use only after VIN, engine, production date, emissions and secondary-air configuration are confirmed Fitment…
- Toyota 17104-38011 genuine right exhaust manifold
replace a test-confirmed cracked or warped right 5.7L exhaust manifold Fitment/availability: Right-side 5.7L 3UR-FE/3UR-FBE branch; the page supersedes 17104-38010 to 17104-38011, and VIN, emissions and secondary-air configuration still …
- Toyota 17105-38011 genuine left exhaust manifold
replace a test-confirmed cracked or warped left 5.7L exhaust manifold Fitment/availability: Left-side 5.7L 3UR-FE/3UR-FBE branch; the page supersedes 17105-38010 to 17105-38011, and VIN, emissions and secondary-air configuration still re…
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Owner tips & cautions
- TipDIY repairs can save significantly - dealer charges $800-$1,500 but DIY costs are typically 50-70% less
- TipConsider OEM parts for critical components like sensors and electrical parts - aftermarket can be unreliable
- TipGet a proper diagnosis before replacing parts - similar symptoms can have different causes
Sources for this issue (1)
Honda Odyssey · 2005–2017
Variable Cylinder Management (VCM) deactivates 3 rear cylinders during light load, but insufficient pressure allows oil to bypass piston rings into 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 class-action lawsuit covering 1.6-1.87 million vehicles.
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.
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
- 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)
Honda Accord · 2008–2012
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 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'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)
RAM 1500 · 2009–2019
Porsche Cayenne · 2011–2018
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P0430 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 P0430 mean?
P0430 stands for "Catalyst System Efficiency Below Threshold (Bank 2)." This code means the catalytic converter on Bank 2 (the side of the engine that does not contain cylinder #1) is not reducing emissions as effectively as it should. The computer compares the readings of the oxygen sensors before and after the converter; if the downstream sensor's signal starts mirroring the upstream one, it indicates the converter is no longer storing and processing oxygen properly. This usually points to a worn-out or damaged catalytic converter, but it can also be caused by faulty sensors or upstream engine problems that have poisoned the converter. The car will generally still run, but it will fail an emissions test.
What are the most common causes of P0430?
The most common causes of P0430 are: Worn-out or failed catalytic converter (Bank 2), Faulty downstream (post-cat) oxygen sensor, Faulty upstream oxygen sensor giving bad data, Exhaust leak near the converter or sensors, Engine misfire or oil/coolant burning that damaged the catalyst, Running too rich or too lean over time, Aftermarket or non-compliant catalytic converter. The specific cause varies by vehicle.
How much does it cost to fix P0430?
Repair costs for P0430 range from $40 to $10,000, depending on the vehicle and root cause.
Which vehicles are affected by P0430?
Au7o has documented P0430 across 48 vehicle models from 21 manufacturers: Acura, Audi, Cadillac, Chevrolet, Chrysler, Dodge, Ford, GMC, Honda, Hyundai, Infiniti, Jeep, Kia, MINI, Mazda, Nissan, Opel, Porsche, RAM, Subaru, Toyota.
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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.