Circuit Description

WARNING: This page is about a different car, the 2002 Oldsmobile Intrigue and 2002 Oldsmobile Aurora. 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 2 heater is fed power directly from ignition 1. The HO2S 2 heater control circuit, or heater ground, is connected to the Powertrain Control Module (PCM). The PCM controls the 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. Each driver has a fault line which is monitored by the PCM. When PCM is commanding a component ON, the voltage on the control circuit should be near 0 volts. When PCM is commanding the control circuit to a component OFF, the voltage potential on the circuit should be near battery voltage. If fault detection circuit senses a voltage other than what is expected, a DTC will set.