Conditions for Setting the DTC

WARNING: This page is about a different car, the 2008 GMC Yukon and 2008 Chevrolet Tahoe. However, it is still accessible from the selected car via links, so may be relevant.

The ECM has determined the catalyst efficiency has degraded below a calibrated threshold.
This diagnostic may conclude in one test attempt. However, this diagnostic may require as many as 24 test attempts, which would require at least 3 drive cycles. Each test attempt may conclude within approximately 1 minute.