DOWNSTREAM OXYGEN SENSOR
The downstream heated oxygen sensor input is used to detect catalytic convertor deterioration. As the convertor deteriorates, the input from the downstream sensor begins to match the upstream sensor input except for a slight time delay. By comparing the downstream heated oxygen sensor input to the input from the upstream sensor, the PCM calculates catalytic convertor efficiency. This is also used to establish the upstream O2 goal voltage (switching point).
Scheme 139
Scheme 139: DOWNSTREAM OXYGEN SENSOR (1/2)
| WARNING | The exhaust manifold, exhaust pipes and catalytic converter(s) become very hot during engine operation. Allow engine to cool before removing oxygen sensor. Failure to allow engine to cool before removal may result in personal injury caused by burns. |
| CAUTION | When disconnecting sensor electrical connector, do not pull directly on wires going into oxygen sensor. Damage to the oxygen sensor may occur. |
Note. Use an oxygen sensor (O2S) removal tool for this procedure.
- Raise and support vehicle.
- Disconnect O2S wire harness mounting clips from engine or body, if equipped.
- Disconnect O2S pigtail harness connector (1) from engine wiring harness.
- Remove O2S (3) from exhaust pipe (2).
Scheme 140
Scheme 140: UPSTREAM OXYGEN SENSOR (1/1)
| WARNING | The exhaust manifold, exhaust pipes and catalytic converter(s) become very hot during engine operation. Allow engine to cool before removing oxygen sensor. Failure to allow engine to cool before removal may result in personal injury caused by burns. |
| CAUTION | When disconnecting sensor electrical connector, do not pull directly on wires going into oxygen sensor. Damage to the oxygen sensor may occur. |
Note. Use an oxygen sensor (O2S) removal tool for this procedure.
- Raise and support vehicle.
- Disconnect O2S wire harness mounting clips from engine or body, if equipped.
- Disconnect O2S pigtail harness connector (1) from engine wiring harness.
- Remove O2S (3) from maniverter (2).
Scheme 141
Scheme 141: DOWNSTREAM OXYGEN SENSOR (1/2)
| WARNING | The exhaust manifold, exhaust pipes and catalytic converter(s) become very hot during engine operation. Allow engine to cool before removing oxygen sensor. Failure to allow engine to cool before removal may result in personal injury caused by burns. |
| CAUTION | When disconnecting sensor electrical connector, do not pull directly on wires going into oxygen sensor. Damage to the oxygen sensor may occur. |
Note. Use an oxygen sensor (O2S) removal tool for this procedure.
- Raise and support vehicle.
- Disconnect O2S wire harness mounting clips from engine or body, if equipped.
- Disconnect O2S pigtail harness connector (1) from engine wiring harness.
- Remove the O2S (3) from catalytic converter (2).
Scheme 142
Scheme 142: UPSTREAM OXYGEN SENSOR (1/1)
| WARNING | The exhaust manifold, exhaust pipes and catalytic converter(s) become very hot during engine operation. Allow engine to cool before removing oxygen sensor. Failure to allow engine to cool before removal may result in personal injury caused by burns. |
| CAUTION | When disconnecting sensor electrical connector, do not pull directly on wires going into oxygen sensor. Damage to the oxygen sensor may occur. |
Note. Use an oxygen sensor (O2S) removal tool for this procedure.
- Raise and support vehicle.
- Disconnect O2S wire harness mounting clips from engine or body, if equipped.
- Disconnect O2S pigtail harness connector (1) from engine wiring harness.
- Remove the O2S (3) from exhaust pipe (2).
