Circuit Description

The powertrain control module (PCM)/engine control module (ECM) supplies a voltage of about .45 volt between terminals C14 and C15 (if measured with a 10 megohm digital voltmeter, this may read as low as .32 volt). The Oxygen Sensor (O2S1) varies voltage within a range of about 1 volt if exhaust is rich, down through about .10 volts if exhaust is lean.

The sensor is like an 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 O2S1 pigtail wiring, connector, or terminal is damaged entire O2S1 assembly must be replaced. Do not attempt to repair wiring, connector, or terminals. In order for sensor to function properly, it must have a clean air reference provided to it. This clean air reference is obtained by way of O2S1 wire(s). Any attempt to repair wires, connector, or terminals could result in obstruction of air reference and degrade O2S1 performance.