DTC P0133: Ho2S Slow Response (Bank 1; Sensor 1 - SOHC): Description
WARNING: This page is about a different car, the 2002 Pontiac Sunfire, 2002 Pontiac Grand Am, 2002 Oldsmobile Alero, and 2002 Chevrolet Cavalier. However, it is still accessible from the selected car via links, so may be relevant.
The Powertrain Control Module (PCM) continuously monitors the Heated Oxygen Sensor (HO2S) 1 activity for 100 seconds. During the monitoring period, the PCM counts the number of times that the HO2S 1 switches from rich-to-lean, and from lean-to-rich, then adds the time that the HO2S 1 took to complete all the switches. With this information, an average time for all switches can be determined. Whenever the average time to switch is too slow, a DTC P0133 will set.