DTC P1133 & P1153: Ho2S Circuit - Insufficient Switching - Bank 1 & 2, Sensor 1 (6.0L W/Isolated Ground): Description
WARNING: This page does not describe the selected car, but rather 11 other vehicles, including the 2002 GMC Yukon XL, 2002 GMC Yukon, 2002 GMC Sierra, 2002 GMC Cab & Chassis Sierra, and 2002 Chevrolet Tahoe. However, it is still accessible from the selected car via links, so may be relevant.
This diagnostic applies only to vehicles built with isolated grounded Heated Oxygen Sensors (HO2S). The Powertrain Control Module (PCM) monitors the HO2S activity for 100 seconds. During this monitor period the PCM counts the number of times that the HO2S switches from rich to lean and lean to rich. A DTC P1133 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.