DTC P1133 & P1153: Ho2S Circuit - Insufficient Switching - Bank 1 & 2, Sensor 1: Description
WARNING: This page is about a different car, the 2002 Pontiac Firebird and 2002 Chevrolet Camaro. However, it is still accessible from the selected car via links, so may be relevant.
The Powertrain Control Module (PCM) monitors the Heated Oxygen Sensor (HO2S) activity for 100 seconds. During this monitoring period, the PCM counts the number of times that the HO2S switches from rich to lean, and from lean to rich. A DTC P1133 or P1153 sets when the PCM determines that the HO2S did not switch enough times. A lean to rich switch is determined when the HO2S voltage changes from less than 300 mV to more than 600 mV. A rich to lean switch is determined when the HO2S voltage changes from more than 600 mV to less than 300 mV.