P0430 on Honda
Catalyst System Efficiency Below Threshold (Bank 2)
P0430 on Honda vehicles indicates catalyst system efficiency below threshold (bank 2). Au7o has documented this code across 5 Honda models — most commonly on Accord, Insight, Odyssey. 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. Typical repair costs on Honda range from $81 to $3,500, depending on the specific model and root cause.
Common Causes of P0430
- •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
P0430 on Honda by Model
Honda Accord(2 issues)
- V6 VCM Excessive Oil Consumption and Engine Vibration2008-2012
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 (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.
- Premature Catalytic Converter Failure - P0420 / P0430 Low Efficiency2008-2017
Accords are a frequent source of P0420 (Bank 1 catalyst below threshold) and, on the J-series V6 with its dual converters, P0430 (Bank 2). While high-mileage catalyst aging is normal, on these cars failures are often accelerated by upstream oil consumption — the K24 sticking-piston-ring oil burn and the V6 VCM oil consumption saturate and poison the catalyst — so a 'bad cat' code is often a symptom of an oil-control problem. A lazy downstream O2 sensor mimics the same code and wastes a cat replacement if not ruled out first.
Honda Insight(1 issue)
- Catalytic Converter Failure (First Gen)2000-2006
The 2000-2006 Honda Insight (first generation) experiences premature catalytic converter failures. The lean-burn engine runs very lean, putting extra stress on the catalytic converter. Symptoms include check engine light with P0420/P0430 codes, rattling noise from exhaust, reduced power, and failed emissions test. OEM Honda catalytic converter: $1,200-2,000. Aftermarket: $400-800.
Honda Odyssey(1 issue)
- VCM Oil Consumption and Piston Ring Failure2005-2017
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.
Honda Passport(1 issue)
- Exhaust Manifold Stud Breakage and Exhaust Leak Tick on 3.2L V62000-2002
The 3.2L V6 used in the first-generation Passport is known to develop exhaust leaks from broken manifold studs or warped manifold sealing surfaces as the vehicle ages. Owners commonly describe a ticking noise on cold start, exhaust smell, and occasional failed emissions testing. Heat cycling and corrosion are the usual causes, and the repair can become labor-intensive if studs snap flush in the cylinder head.
Honda Pilot(2 issues)
- Fuel Injector Debris Causing Misfires and Catalyst Codes2016-2018
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.
- Catalytic Converter Efficiency Failure Triggering P0420 / P04302003-2018
The Pilot's three-way catalytic converters lose conversion efficiency with age and contamination, setting P0420 (Bank 1) and/or P0430 (Bank 2) and illuminating the check engine light. Symptoms include reduced power/fuel economy, a rotten-egg (sulfur) smell, and a rattle from a broken internal substrate. Note: on 2016-2018 Pilots these catalyst codes are very often caused upstream by failing fuel injectors (covered by Honda TSB 20-100 and a 10yr/150k warranty extension), so a full diagnosis is essential before condemning the converter.
Looking for P0430 on a different make?
View P0430 across all makes →Frequently Asked Questions
What does P0430 mean on Honda?▼
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. On Honda specifically, this code is documented across 5 models.
What causes P0430 on Honda vehicles?▼
Common causes on Honda: 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. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P0430 on a Honda?▼
Repair costs on Honda range from $81 to $3,500, depending on the specific model and root cause.
Which Honda models have P0430 documented?▼
Au7o has documented P0430 on 5 Honda models: Accord, Insight, Odyssey, Passport, Pilot.