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.
The Powertrain Control Module (PCM) supplies a bias voltage of about 450 millivolts between the Heated Oxygen Sensor (HO2S) high signal circuit and the HO2S low reference circuit. When measured with a 10-megohm digital voltmeter, this voltage may be as low as 350 millivolts. The HO2S high signal varies from about 800 millivolts when the exhaust is rich, to about 50 millivolts when the exhaust is lean. If HO2S 2 voltage remains at or near 450 millivolts bias for an extended period of time, DTC P0140 will set