Heated Oxygen Sensor

How To Switch Diagnostic Test Modes:

HOW TO CHECK HEATED OXYGEN SENSOR (HO2S)
Set Diagnostic Test Mode II. (Refer to figure, "HOW TO SWITCH DIAGNOSTIC TEST MODES".)

Heated Oxygen Sensor:

NOTE: Two heated oxygen sensors (right bank and left bank) are fitted on the engine, the left bank heated oxygen sensor monitor operates first, when selecting this mode. It is necessary to manually switch the monitor function to the right bank heated oxygen sensor in order to view its operation.

Procedure
- Start engine and warm it up until engine coolant temperature indicator points to the middle of the gauge.
- Run engine at about 2,000 rpm for about 2 minutes under no-load conditions.

Engine Control Module's Red L.E.D. (Light Emiting Diode):

Malfunction Indicator Lamp (MIL):

- Make sure the RED, Light Emitting Diode (LED) in the Engine Control Module (ECM) or the MALFUNCTION INDICATOR LAMP (MIL) goes ON and OFF more than 5 times every 10 seconds; measured at 2,000 rpm under no-load.

- Repeat the same test for the right side HO2S after changing the monitor function from left to right. Refer to procedure below.

How To Change Monitor from Left Bank to Right Bank and Vise-Versa.
- Turn diagnostic test mode selector on ECM fully clockwise.
- Wait at least 2 seconds.
- Turn diagnostic test mode selector on ECM fully counterclockwise.

NOTE: These procedures should be carried out when the engine is running.

Heated Oxygen Sensor, Heater Insp.:

HEATED OXYGEN SENSOR HEATER
Perform test with engine OFF and ignition key in the OFF position.
- Disconnect the Heated Oxygen Sensor (HO2S) connector from the vehicle harness.
- Using a suitable Ohm meter, measure the resistance across the specified terminals in the HO2S "pigtail" side of the connector as shown in image.

Resistance between terminals (a) and (c): 3 - 1000 Ohms.

- If Not Good. Replace HO2S assembly.