Oxygen Sensor

Warm engine to operating temperature. Connect positive voltmeter probe to O2 sensor terminal of check connector. See the CHECK CONNECTOR LOCATION table in this article. Connect negative probe to terminal "E1". See:
- Fig. Fig 1 for Corolla.
- Fig. Fig 2 for Pickup.
- Fig. Fig 3 for Tercel.
Start engine and increase speed to 2500 RPM for 90 seconds. Maintain 2500 RPM and monitor voltmeter needle. Voltmeter should fluctuate at specified voltage for the minimum amount within 10 seconds. See OXYGEN O2 SENSOR VOLTAGE FLUCTUATION table in this article.
If O2 sensor is not operating properly, check each component, hose and wiring of carburetor feedback system. If a problem is not found, replace O2 sensor.

OXYGEN O2 SENSOR VOLTAGE FLUCTUATION

Fig 1: O2 Sensor Check Connector Terminal Identification (Corolla)

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Fig 2: O2 Sensor Check Connector Terminal ID (Pickup)

Fig 3: O2 Sensor Check Connector Terminal Identification (Tercel)