Subaru IMPREZA GD 2007 Series Manual page 1861

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Diagnostic Trouble Code (DTC) Detecting Criteria
GENERAL DESCRIPTION
2) Judge as NG when the oxygen sensor voltage at recovery from a deceleration fuel cut, is large.
If the fuel cut time in a deceleration fuel cut is long (6 s or more), and even after recovering from a deceler-
ation fuel cut, the oxygen sensor voltage is high (0.55 V or more), judge as NG.
Judgment Value
Malfunction Criteria
Shortest time change from rich (500 mV
O output) to lean (200 mV) when volt-
2
age reduces from 550 mV to 150 mV
Time at 550 mV or more
Time Needed for Diagnosis: 1 time
Malfunction Indicator Light Illumination: Illuminates when malfunction occurs in two continuous driving
cycles.
Normality Judgment
1) Regardless of a deceleration fuel cut, if the response time (diagnosis value) when the oxygen sensor volt-
age has changed from rich to lean is shorter than the threshold value (judgment value), judge as a normal
condition.
Response time (diagnosis value) ≤ threshold value → normal
2) Do not judge as a normal condition.
Judge as OK when the criteria below are met.
Judgment Value
Malfunction Criteria
Shortest time change from rich (500 mV
O output) to lean (200 mV) when volt-
2
age reduces from 550 mV to 150 mV
6. DTC CLEAR CONDITION
• When the OK idling cycle is completed 40 times in a row
• When "Clear Memory" is performed
7. MALFUNCTION INDICATOR LIGHT CLEAR CONDITIONS
• When the OK driving cycle is completed three times in a row
• When "Clear Memory" is performed
8. FAIL SAFE
Sub feedback control: Not allowed
9. ECM OPERATION AT DTC SETTING
• Memorize the freeze frame data. (For test mode $02)
• Memorize the diagnostic value and trouble standard value. (For test mode $06)
10.ENABLE CONDITION
• Lean → rich response diagnosis
Secondary Parameters
Battery voltage
A/F main feedback control condition
Deceleration fuel cut ≥ 5 seconds
After fuel cut
Current calculation time of the rear oxy-
gen sensor heater
Current continuation time of the rear oxy-
gen sensor heater
Threshold Value
> 0.837 seconds
> 2 seconds
Judgment Value
≤ 0.837 seconds
Enable Conditions
> 10.9 V
Completed
Experienced
≥ 2 seconds
≥ 60 seconds
≥ 30 seconds
GD(H4DOTC)-70