Oxygen Sensor: Testing and Inspection

1. Note the following during this test:
a. Avoid damaging wiring harness.
b. To prevent cross threading, first tighten finger tight, then torque to 33 ft. lbs.
c. Oxygen sensor does not operate when its intake is clogged.
d. Be extremely careful not to spray water over oxygen sensor.
2. Raise and support front of vehicle, block rear wheels and apply parking brake.
3. Attach positive probe of voltmeter to No. 31 white terminal and negative terminal to No. 32 black terminal of control unit connector.
4. Start engine and warm up for 2 minutes at 3000 RPM under no load, then raise engine speed to 4000 RPM and release throttle suddenly at least 5 times.
5. Within 1 minute after engine has been warmed up, measure voltage as follows. If it takes more than 1 minute to complete step 4, warm up engine as in step 3 before continuing.
a. At idle, voltage should be above .6 volt.
b. Place shift or selector lever in second or 2 position and raise engine speed to 5000 RPM, then lower to 1500 RPM by operating accelerator pedal. Voltage should be below .4 volt.
6. If voltages are not as described in step 5, replace oxygen sensor.