2.4L Engine Upstream (6-Wire)
| OXYGEN SENSOR COMPONENTS | |
|---|---|
| CALLOUT | DESCRIPTION |
| 1. | Measuring cell (Nernst cell and pumping cell) |
| 2. | Protective tube |
| 3. | Seal |
| 4. | Sealing cover |
| 5. | Casing |
| 6. | Protective skirt |
| 7. | Contact support |
| 8. | Contact spring |
| 9. | Teflon wire-lead |
| 10. | Profile hose |
| 11. | Junction wires |
| 12. | Seal |
The wide-band (6-Wire) O2 Sensor operates differently than the traditional 4-Wire O2 Sensor. The wide-band O2 Sensor tip consists of two cells that provide different functions, a measurement chamber and a detection chamber with pumping capabilities. The oxygen pumping function is the ability to pump oxygen into or out of the measurement chamber depending on the level of oxygen in the measurement chamber. This function provides the wide-band sensing capabilities and is critical for proper oxygen measurement. The O2 Sensor Positive Current Control circuit provides a common bias supply to both the O2 Sensor Signal and the O2 Sensor Pump Cell Current circuits.
During normal operation, the O2 Sensor Positive Current Control voltage and O2 Sensor Signal voltage will be a fixed voltage value. The O2 Sensor Pump Cell Current voltage will switch from approximately 0.45 volts above and below the fixed O2 Sensor Return voltage, allowing current to flow in either direction through the pump. This correlates with the pumping of oxygen into and out of the measurement chamber. On a properly operating vehicle, this happens very quickly and the voltage reading will appear as a steady 0.45 volts when taking a voltage measurement between the O2 Sensor Signal circuit and the O2 Sensor Positive Current Control circuit of the O2 Sensor with the engine running and the O2 Sensor operating in closed loop.
When the exhaust stream (3) has a lean air/fuel ratio with high oxygen content (1) the Pump Cell Current voltage will move toward +0.45 volts pumping oxygen out of the measurement chamber (2).
When the exhaust stream has a rich air/fuel ratio with relatively low oxygen content (1) the Pump Cell Current voltage will move toward -0.45 volts pumping oxygen into the measurement chamber (2).