DTC Confirmation Test (Overall Function Check)

NOTE: Use the following test to check closed-loop fuel control. During this test, DTC may not be confirmed.

Malfunction is detected when ECM does not operate in closed loop. Possible causes are:

Front HO2S circuit open or shorted.
Defective front HO2S.
Defective front HO2S heater.

To check closed-loop operation, start engine and warm to normal operating temperature. Measure voltage between ground and ECM terminals No. 63 (for right HO2S) and No. 62 (for left HO2S) by backprobing. See Figure and Figure . Monitor voltmeter with engine at 2000 RPM. Voltage should be less than .21 volt at least once, and more than .70 volt at least once.