What causes P0430 on a GMC Sierra 1500?

Common causes of P0430 on GMC Sierra 1500: Degraded catalytic converter on Bank 2 (common on high-mileage GM V8s); Oil consumption from AFM lifter issues contaminating the catalyst; Failed downstream O2 sensor on Bank 2 giving false catalyst reading; Exhaust leak before the catalytic converter; Engine running rich on Bank 2 poisoning the catalyst.

P0430

P0430 GMC Sierra 1500

Q: How much does it cost to fix P0430 on a GMC Sierra 1500?

Fixes for P0430 on GMC Sierra 1500 include: Replace Bank 2 catalytic converter with CARB-compliant or OE unit, First verify downstream O2 sensor is functioning correctly, Address any engine oil consumption issues (AFM lifters, piston rings) to prevent repeat failure, Check for exhaust manifold leaks or broken bolts, Verify no rich condition exists on Bank 2 before replacing converter.

Catalyst System Efficiency Below Threshold (Bank 2) · Powertrain Code · Medium

What is P0430?

The catalytic converter on bank 2 is not operating efficiently. Same as P0420 but for the opposite bank.

When the GMC Sierra 1500 triggers code P0430 (catalyst system efficiency below threshold (bank 2)), it typically points to an issue in the powertrain system. Below you'll find the most common causes, symptoms, and repair options specific to the GMC Sierra 1500.

Diagnostic data on this page is compiled from publicly available repair resources and technical service bulletins. Always have a qualified mechanic confirm the diagnosis before authorizing repairs on your GMC Sierra 1500.

Common Causes on GMC Sierra 1500

Degraded catalytic converter on Bank 2 (common on high-mileage GM V8s)
Oil consumption from AFM lifter issues contaminating the catalyst
Failed downstream O2 sensor on Bank 2 giving false catalyst reading
Exhaust leak before the catalytic converter
Engine running rich on Bank 2 poisoning the catalyst

Symptoms

Check Engine Light on
Failed emissions inspection
Possible sulfur (rotten egg) smell from exhaust
Slight power loss in severe cases
Reduced fuel economy

Recommended Fixes

Replace Bank 2 catalytic converter with CARB-compliant or OE unit

First verify downstream O2 sensor is functioning correctly

Address any engine oil consumption issues (AFM lifters, piston rings) to prevent repeat failure

Check for exhaust manifold leaks or broken bolts

Verify no rich condition exists on Bank 2 before replacing converter

Notes for GMC Sierra 1500

On GM 5.3L V8s with oil consumption issues, replacing the catalytic converter without fixing the oil consumption will result in premature converter failure again.

P0430 GMC Sierra 1500

What is P0430?

Common Causes on GMC Sierra 1500

Symptoms

Notes for GMC Sierra 1500

Check GMC Sierra 1500 Specs