Circuit Description

The Engine Control Module (ECM) supplies a voltage of about 0.45 V between terminals E34 and E26 (if measured with a 10 MO digital voltmeter, this may read as low as 0.32 V). The Heated Oxygen Sensor 1 (HO2S1) varies the voltage within a range of about 1 V if the exhaust is rich, down through about 0.10 V if the exhaust is lean. The sensor is like and open circuit and produces no voltage when it is below 315 °C (600 °F). An open sensor circuit or cold sensor causes Open Loop operation.

If the HO2S1 pigtail wiring, connector, or terminal is damaged, the entire HO2S1 assembly must be replaced. Do not attempt to repair the wiring, connector, or terminals. In order for the sensor to function properly, it must have a clean air reference provided to it. This clean air reference is obtained by way of the HO2S1 wire (s). Any attempt to repair the wires, connector or terminals could result in the obstruction of the air reference and degrade the HO2S1 performance. Refer to "Heated Oxygen Sensor 1".