Subaru IMPREZA GD 2007 Series Manual page 2137

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Diagnostic Trouble Code (DTC) Detecting Criteria
GENERAL DESCRIPTION
5. DIAGNOSTIC METHOD
When the oxygen sensor output voltage changes from 0.55 V (rich) to 0.15 V (lean), calculate the minimum
response time for output change between 0.5 V and 0.2 V for the judgment criteria.
Diagnosis execution condition
Rear oxygen sensor (V)
0V
Fuel cut on deceleration
Abnormality Judgment
1) Judge as NG when the judgment value is larger than the threshold value after deceleration fuel cut.
Response time (diagnosis value) > threshold value → abnormal
NOTE:
Variation time of rear oxygen sensor output voltage is short during fuel cut in deceleration. NG judgment
should be performed after deceleration fuel cut. Even without deceleration fuel cut, judge as OK if the value
is below the threshold.
When the deceleration fuel cut time is 6 seconds or more, judge as NG if the following criteria are met 2 sec-
onds after recovering from the deceleration fuel cut.
0.55V
0.5V
0.2V
0.15V
More than 6 seconds
GD(STI)-70
Measure the response time.
Execute the malfunction judgment
2 seconds after the recovery of fuel.
EN-05554