Legacy Sedan 2WD F4-2.2L SOHC (1990)
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Oxygen Sensor Testing
CHECK ECU VOLTAGE
With engine warmed up and idling, measure voltage between ECU connector terminal (B48)6 and ground. It should read 0.1-1.0V.
NOTE: Problems with the oxygen sensor heater circuit will cause the sensor to deactivate.
CHECK OXYGEN SENSOR
1.
With engine idling at operating temperature, disconnect oxygen sensor connector.
2.
Measure voltage between oxygen sensor terminal #4 and ground. It should read 0.1-1.0V.
CHECK HARNESS BETWEEN ECU AND OXYGEN SENSOR
1.
Disconnect ECU and oxygen sensor connectors.
2.
Measure resistance between ECU and oxygen sensor connectors and ground as follows:
Connector & terminal:
Resistance:
(B48)6-(B20)4
0 Ohms
(B20)4-Ground
1M Ohms min.