Oxygen Sensor: Testing and Inspection

Fig. 23 Oxygen sensor test connections:

1. On engines equipped with high altitude control system, disconnect vacuum hose between high altitude control valve and check valve at check valve and plug check valve.
2. Connect voltmeter to service connector, Fig. 23.
3. Run engine at 2500 RPM for approximately 90 seconds, then, maintaining engine speed, check that needle of voltmeter fluctuates at least 8 times in 10 seconds within zero to 7 volts range.
4. Reconnect vacuum hoses and air hoses to proper locations.
5. If test results are not as described, check other components, connections, and wiring of air injection system. If no problem is found, replace oxygen sensor.