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Diagnostic Method

WARNING: This page is about a different car, the 2012 Subaru Forester. However, it is still accessible from the selected car via links, so may be relevant.
JUDGMENT VALUE REFERENCE CHART (INTERMEDIATE)

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
or
Longest time over 0.55 V
≥ 2000 ms
JUDGMENT VALUE REFERENCE CHART (WIDE)

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 > Value from Map
or
Longest time over 0.65 V
≥ 2000 ms
ENABLE CONDITION REFERENCE CHART

Estimated temperature of rear oxygen sensor element when fuel cut starts °C (°F) 0 (32) 450 (842) 480 (896) 500 (932) 1000 (1832)
Longest time in rich status after fuel cut (ms) 2000 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 REFERENCE CHART (INTERMEDIATE)

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 REFERENCE CHART (WIDE)

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 Output Voltage Graph
G07669709Courtesy of SUBARU OF AMERICA, INC.
JUDGMENT VALUE REFERENCE 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
or
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 REFERENCE 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)