P0430 Chevy Silverado: Catalyst Efficiency Below Threshold Bank 2

P0430 on a Chevy Silverado indicates the catalytic converter on Bank 2 (passenger side) is operating below efficiency requirements. It’s the Bank 2 equivalent of P0420. The diagnosis process and fixes are nearly identical — just applied to the passenger-side exhaust.

What P0430 Means

The ECM monitors the upstream and downstream O2 sensors on Bank 2 (passenger side on most GM V8s). When the downstream sensor starts mirroring the upstream sensor too closely — indicating the catalyst isn’t converting exhaust gases properly — P0430 is stored. On most Silverado V8s, Bank 2 is the passenger side exhaust.

Diagnosis Approach

Check the Bank 2 downstream O2 sensor (sensor 2) before condemning the catalytic converter. An exhaust leak between the engine and the cat on Bank 2 can also trigger P0430 by admitting outside air. Check for oil consumption — if the engine burns oil, the catalyst will be oil-fouled. Inspect the passenger-side exhaust manifold for cracks or warping.

When Both P0420 and P0430 Are Set

If both P0420 and P0430 are stored, the most likely scenario is engine-level contamination (oil burning, coolant leak into combustion) poisoning both catalysts. Both converters don’t usually fail independently at the same time unless the truck has very high mileage. Check for blue exhaust smoke and oil consumption before buying two catalytic converters.

Repair Costs

Bank 2 catalytic converter replacement: $150–400 aftermarket, $300–600 OEM. Labor: $200–400. Downstream O2 sensor replacement: $30–80 parts + $50–100 labor. A complete dual-bank cat replacement with O2 sensors runs $600–1,200 at a shop — do both sides at once if both are worn.