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Home >> Subaru >> 2010 >> Outback Limited >> Repair and Diagnosis (Single Page) >> Engine Performance >> System >> Diagnostic Trouble Code (DTC) Detecting Criteria (H4SO) >> Diagnostic Trouble Code (DTC) Detecting Criteria >> DTC P0139 O2 Sensor Circuit Slow Response (Bank 1 Sensor 2) >> Diagnostic Method
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Diagnostic Method

Judge as NG when oxygen sensor voltage is large even after a long period of deceleration fuel cut has completed.

Judgment value (Intermediate) 

JUDGMENT VALUE CHART

Malfunction Criteria Threshold Value
Shortest time change from rich (0.5 V O2 output) to lean (0.2 V) when voltage reduces from 0.55 V to 0.15 V
or
> 491 ms
Longest time over 0.55 V ≥ 2000 ms

Judgment value (Wide) 

JUDGMENT VALUE CHART

Malfunction Criteria Threshold Value
Shortest time change from rich (0.6 V O2 output) to lean (0.1 V) when voltage reduces from 0.65 V to 0.05 V
or
> Value from Map
Longest time over 0.65 V ≥ 2000 ms

Map 

MAP SPECIFICATION CHART

Estimated temperature of rear oxygen sensor element when fuel cut starts °C (°F) 0 (32) 450 (842) 500 (932) 1000 (1832)
Longest time in rich status after fuel cut (ms) 2000 2000 2000 2000

Time Needed for Diagnosis:  1 time(s)

Malfunction Indicator Light Illumination:  Illuminates when malfunction occurs in 2 continuous driving cycles.

Judgment value (Intermediate) 

JUDGMENT VALUE CHART

Malfunction Criteria Threshold Value
Shortest time change from rich (0.5 V O2 output) to lean (0.2 V) when voltage reduces from 0.55 V to 0.15 V ≤ 491 ms

Judgment value (Wide) 

JUDGMENT VALUE CHART

Malfunction Criteria Threshold Value
Shortest time change from rich (0.6 V O2 output) to lean (0.1 V) when voltage reduces from 0.65 V to 0.05 V ≤ 2000 ms

Time Needed for Diagnosis:  1 time(s)



When the oxygen sensor output voltage changes from 0.25 V (lean) to 0.55 V (rich), calculate the minimum response time for output change between 0.3 V and 0.5 V for the judgment criteria.

Fig 1: Rear Oxygen Sensor Voltage Waveform
G06651105Courtesy of SUBARU OF AMERICA, INC.

Judgment Value 

JUDGMENT VALUE CHART

Malfunction Criteria Threshold Value
Shortest time change from lean (0.3 V O2 output) to rich (0.5 V) when voltage changes from 0.25 V to 0.55 V
or
> 4000 ms
Longest time under 0.25 V ≥ 120000 ms

Time Needed for Diagnosis:  1 time(s)

Malfunction Indicator Light Illumination:  Illuminates when malfunction occurs in 2 continuous driving cycles.

Judgment Value 

JUDGMENT VALUE CHART

Malfunction Criteria Threshold Value
Shortest time change from lean (0.3 V O2 output) to rich (0.5 V) when voltage changes from 0.25 V to 0.55 V ≤ 4000 ms

Time Needed for Diagnosis:  1 time(s)