Front Heated Oxygen Sensor

Front Heated Oxygen Sensor Test:

PROCEDURE 1 - AT COMPONENT
1. Check resistance between terminals (a) and (c).
Resistance: 4.8 ±1.5 Ohms at 25°C (77°F)
2. Check continuity between terminals (b) and (c), (a) and (b).
Continuity should not exist.
3. If NG, replace heated oxygen sensor.

HO2S Operation Chart:

PROCEDURE 2 - USING DIAGNOSTIC TEST MODE II-FRONT HEATED OXYGEN SENSOR MONITOR
In this mode, the MALFUNCTION INDICATOR LAMP displays the condition of the fuel mixture (lean or rich) which is monitored by the front heated oxygen sensor.
To check the front heated oxygen sensor function, start engine in the Diagnostic Test Mode II and warm it up until engine coolant temperature indicator points to the middle of the gauge.
Next run engine at about 2,000 rpm for about 2 minutes under no-load conditions. Then make sure that the MALFUNCTION INDICATOR LAMP goes ON and OFF more than 5 times every 10 seconds when measured at 2,000 rpm under no-load.

FRONT HEATED OXYGEN SENSOR HEATER

Front HO2S Heater Test:

1. Check resistance between terminals (a) and (c).
Resistance: 4.8 ±1.5 Ohms at 25°C (77°F)
2. Check continuity between terminals (b) and (c), (a) and (b).
Continuity should not exist.
3. If NG, replace heated oxygen sensor.