Conditions for Setting the DTC

WARNING: This page is about a different car, the 2007 Chevrolet Cobalt. However, it is still accessible from the selected car via links, so may be relevant.

The PCM has determined the catalyst efficiency has degraded below a calibrated threshold.
This diagnostic may conclude in 6 test attempts which will require at least 2 drive cycles. However, this diagnostic may require as many as 8 test attempts. Depending on driving conditions, more than 2 drive cycles may be required. Each test attempt may conclude within approximately 1 minute.