P0430 Catalyst System Efficiency Below Threshold

The other day the engine light came on in the 2008 H3 Hummer Alpha with the 5.3L V8. I took out my handy scan tool and checked the error code with the Android App Torque Pro to see what’s up.

Fault code: P0430 Catalyst System Efficiency Below Threshold (Bank 2)

After some Google-ing, I found a lot of people on the Hummer Forums immediately changing out the catalytic converter. I’ve never had a bad catalytic converter on any of the vehicles owned. However, I have replaced a bunch of 02 sensors over the years. This is why I choose to have Rockauto.com ship a brand new downstream 02 sensor to my door for $50, rather than immediately replacing one of the $300 catalytic converters. I even read about a K&N air filter possible causing the P0430 engine code.

Hopefully, the engine code is just a simple fix, I’ll report back.

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