Conditions for Setting the DTCs (w/o LLT)
WARNING: This page is about a different car, the 2008 Cadillac CTS. However, it is still accessible from the selected car via links, so may be relevant.
The ECM determines that the length of time for an HO2S 1 to switch from lean to rich and back to lean, which is called a switching cycle, has exceeded a predetermined threshold. The condition exists for 3 cycles out of a 20 cycle test sample.