Oxygen (O2) Sensor Check

Warm vehicle to normal operating temperature. Connect positive voltmeter probe to O2 sensor terminal of check connector. See CHECK CONNECTOR LOCATION table in this article. Connect negative probe to terminal "E1". See Fig 1 and Fig 2 .

CHECK CONNECTOR LOCATION

Vehicle

Location

Tercel Sedan

⁽¹⁾ Next to Clutch Reservoir, on Firewall

Tercel Wagon

⁽¹⁾ Right Fender Below Wiper Motor

⁽¹⁾	See Fig 1 and Fig 2.

Start engine and increase RPM to 2500 RPM for 90 seconds. Maintain 2500 RPM and monitor voltmeter needle. Voltmeter should fluctuate specified volts, 8 times or more within 10 seconds. See OXYGEN O2 SENSOR VOLTAGE FLUCTUATION table in this article.

OXYGEN O2 SENSOR VOLTAGE FLUCTUATION

Vehicle	Voltage
Tercel Sedan	1-5
Tercel Wagon	0-7

If check tests okay, O2 sensor is operating properly. If check fails, check each component, hose and wiring of feedback system. If no problem is found, replace O2 sensor.

Fig 1: Tercel Sedan O2 Sensor & Check Connector

Fig 2: Tercel Wagon O2 Sensor & Check Connector