Oxygen Sensor: Testing and Inspection

HEATED OXYGEN SENSORS
^ If a heated oxygen sensor or circuit has an open or short, Diagnostic Trouble Code No. PO131, P0133, P0135, P0136, P0141, PO151, PO153 or PO155 is output.
^ If a heated oxygen sensor circuit fails, poor fuel economy may occur.

INSPECTION OF VOLTAGE
1. Warm up the engine to normal operating temperature and stop it.
2. Disconnect the heated oxygen sensor connector.
3. Connect a voltmeter to the heated oxygen sensor.
4. Start the engine and increase engine speed to 2000 rpm.
5. Check that the voltage changes between 0.2-1.0 V when accelerating and decelerating.

INSPECTION OF HEATER
1. Disconnect the heated oxygen sensor connector.
2. Measure the resistance between the heater terminals.

Resistance 2-5 ohms @ 20°C (68°F)
Hot to warm resistance: 5-30 ohms

3. If not as specified, replace the heated oxygen sensor(s).