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P0430 Catalyst System Efficiency Below Threshold (Bank 2)

What it means

Same as P0420 but for bank 2 (the side of a V6/V8 engine without cylinder 1). The bank 2 catalytic converter isn't performing efficiently.

Severity: Moderate

Can I drive it? Generally drivable short-term; will fail emissions. Fix any misfires promptly to protect the converter.

Common causes (most likely first)

Worn bank 2 catalytic converter
Faulty bank 2 downstream O2 sensor
Exhaust leak
Misfire or rich condition on bank 2

Likely fixes

Rule out exhaust leaks and misfires
Test/replace bank 2 downstream O2 sensor
Replace bank 2 catalytic converter

DIY parts cost

$40–$600

Approximate estimate

Shop repair cost

$200–$2,500

Approximate estimate, parts + labor

DIY difficulty

Moderate

Varies by vehicle

Cost ranges are rough, approximate U.S. estimates and vary widely by vehicle, region, and parts brand. Always confirm the diagnosis before buying parts.

Parts you may need

Downstream oxygen sensorCheck price
Catalytic converterCheck price
O2 sensor socketCheck price
Exhaust gasketCheck price

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