DTC P0135 & P0141: Ho2S Heater Circuit - Sensors 1 & 2: Description
WARNING: This page is about a different car, the 2002 Oldsmobile Bravada, 2002 GMC Envoy XL, 2002 GMC Envoy, and 2002 Chevrolet TrailBlazer. However, it is still accessible from the selected car via links, so may be relevant.
Heated Oxygen Sensors (HO2S) are used to minimize the amount of time required to enter Closed Loop fuel control operation and to allow accurate catalyst monitoring. The HO2S heater is fed power directly from ignition 1. The HO2S heater control circuit or heater ground is connected to the Powertrain Control Module (PCM). The PCM controls HO2S heater operation by grounding the control circuit via an internal solid state device called a driver. The primary function of the driver is to supply the ground for the component being controlled. The driver for the HO2S heater control circuit has the ability to measure the amount of current drawn by the controlled device.