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 Sensor (HO2S) is used to detect oxygen content in the exhaust. The Powertrain Control Module (PCM) supplies HO2S with a signal circuit and a ground circuit. The PCM supplies a bias voltage between the circuits. The HO2S varies voltage based on oxygen content in the exhaust. When exhaust stream is lean (more oxygen), HO2S produces a low voltage signal. When exhaust stream is rich (less oxygen), HO2S produces a high voltage signal. The PCM monitors HO2S activity to determine a time ratio for lean-to-rich switches, and for rich-to-lean switches. The PCM counts number of lean-to-rich and rich-to-lean switches for 100 seconds. The PCM records time required to complete all transitions. With this information, PCM determines an average transition time for lean-to-rich switches and for rich-to-lean switches.

NOTE: HO2S bank 1; sensor 1 is located in right (rear) exhaust manifold.