Main Catalyst Efficiency Below Threshold (Bank 1)

Yes. The vehicle drives normally with a failing main catalyst. Emissions output increases, so you will fail an emissions test. Extended driving with a failing cat will not damage the engine.

OEM catalytic converters range from $300-$1200 for the part alone. Aftermarket options are available for $150-$500. Labor typically adds $100-$300 depending on accessibility.

In many states, a CARB-compliant aftermarket converter is acceptable. However, California and some states require specific CARB-certified converters. Check your local regulations before purchasing.

California's OBD II regulation — the rule that defines when an OBD system must set an emissions code — requires the system to flag the catalyst when its conversion capability drops far enough that Non-Methane Organic Gas emissions would exceed 1.75 times the FTP full-useful-life standard (Title 13 CCR 1968.2, section (e)(1.2)). So the code is not reporting that the converter is dead; it is reporting that measured efficiency crossed the line the monitor was calibrated to. This is the threshold the monitor is designed around, not a description of your specific fault — the regulation says what the system must detect, not how to find it on your vehicle.