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How do I Test the O2 Sensor in a 1987 22RE?
- 1). Start the vehicle and allow it to warm up to operating temperature. The oxygen sensor must be in closed loop to perform the test. Connect the graphing meter's red lead to the harness side of the oxygen sensor connector. Connect the black lead to a known good ground.
- 2). Raise the idle to 2,500 rpm. The minimum voltage should be below 250 mV, and maximum voltage should be more than 800 mV. The minimum voltage should not be a negative number. The oxygen sensor should cycle from high to low eight to 16 times in about 10 seconds, giving you a minimum and maximum reading.
- 3). Snap the throttle several times while watching the graphing meter. When you snap the throttle, the voltage should rise quickly, to more than 850 mV, then come back down.
- 4). Hold the rpm at 2,500. Quickly release the throttle while watching the graphing meter. Voltage should drop quickly to about 100 mV.