Conditions for Setting the DTC
WARNING: This page is about a different car, the 2006 Buick LaCrosse and 2006 Buick Allure. However, it is still accessible from the selected car via links, so may be relevant.
The PCM determines that the efficiency of the catalyst has degraded below a calibrated threshold. This diagnostic may conclude in as few as one test attempt. However, this diagnostic may require as many as 18 test attempts, which would require at least 3 drive cycles. Each test attempt concludes within 2 minutes.