P0430 on Toyota
Catalyst System Efficiency Below Threshold (Bank 2)
P0430 on Toyota vehicles indicates catalyst system efficiency below threshold (bank 2). Au7o has documented this code across 5 Toyota models — most commonly on 4Runner, Celica, MR2. 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 Toyota range from $500 to $3,000, 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 Toyota by Model
Toyota 4Runner(1 issue)
- Cracked Exhaust Manifolds on 4.7L V8 Causing Ticking Noise and Exhaust Leaks2003-2009
The 2UZ-FE V8 in 4th-generation 4Runners is known for exhaust manifold cracking, especially as the vehicle ages and heat cycles accumulate. Owners usually hear a cold-start ticking or tapping from the engine bay that quiets somewhat as the manifolds warm up, and some eventually get catalyst-efficiency or oxygen-sensor-related codes due to exhaust leaks. The issue is well documented in owner forums and repair shops because manifold replacement is labor-intensive and often expensive on both banks.
Toyota Celica(1 issue)
- Pre-Catalytic Converter Disintegration2000-2005
The pre-catalytic converter (integrated into the exhaust manifold) on 2000-2005 Celicas can disintegrate internally, sending ceramic fragments back into the engine through exhaust valve overlap. This causes scoring of cylinder walls and accelerated engine wear. The pre-cat material breaks down from age and heat cycling. Removing or gutting the pre-cat and installing a proper downstream catalytic converter is the standard community fix, though emissions compliance varies by state.
Toyota MR2(1 issue)
- Pre-Catalytic Converter Disintegration (Spyder)2000-2005
The pre-catalytic converter on 2000-2005 MR2 Spyders can disintegrate internally, sending ceramic material back into the engine cylinders during exhaust valve overlap. This is the same issue affecting all 1ZZ-FE-equipped Toyotas of this era. The ceramic debris scores cylinder walls and accelerates engine wear. Early removal or replacement of the pre-cat is considered essential preventive maintenance in the MR2 community.
Toyota Sequoia(1 issue)
- Exhaust Manifold Cracking (4.7L 2UZ-FE V8)2001-2007
The cast iron exhaust manifolds on the 2001-2007 Sequoia 4.7L V8 develop cracks from repeated thermal cycling. The cracks typically appear at the flange where the manifold bolts to the cylinder head or between the runner tubes. A cracked manifold causes an audible exhaust leak (ticking noise on cold start that fades as the manifold expands when hot), a faint exhaust smell near the engine bay, and can eventually trigger a check engine light for catalyst efficiency if exhaust gases bypass the catalytic converter.
Toyota Tundra(1 issue)
- Exhaust Manifold Cracking and Bolt Failure2007-2019
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.
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View P0430 across all makes →Frequently Asked Questions
What does P0430 mean on Toyota?▼
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 Toyota specifically, this code is documented across 5 models.
What causes P0430 on Toyota vehicles?▼
Common causes on Toyota: 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 Toyota?▼
Repair costs on Toyota range from $500 to $3,000, depending on the specific model and root cause.
Which Toyota models have P0430 documented?▼
Au7o has documented P0430 on 5 Toyota models: 4Runner, Celica, MR2, Sequoia, Tundra.