Subaru IMPREZA GD 2007 Series Manual page 1864

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Diagnostic Trouble Code (DTC) Detecting Criteria
AG:DTC P0140 O2 SENSOR CIRCUIT NO ACTIVITY DETECTED
(BANK 1 SENSOR 2)
1. OUTLINE OF DIAGNOSIS
Detect abnormalities in the rear oxygen sensor output characteristics.
By referring to the intake air amount, engine coolant temperature, main feedback control, deceleration fuel
cut and other operating conditions, if the rear oxygen sensor voltage should be moving under these condi-
tions but is showing a low voltage, this is judged as a Low side NG. If the voltage is showing a high voltage,
it is judged as a High side NG.
When either Low side or High side is NG, judged as rear oxygen sensor property NG.
2. ENABLE CONDITION
Secondary Parameters
Engine coolant temperature
Target output voltage of rear oxygen sen-
sor
Air intake amount
Battery voltage
Closed loop at the oxygen sensor
Misfire detection every 200 rotations
Front oxygen (A/F) sensor compensation
coefficient
Deceleration fuel cut of 5 seconds or
more.
3. GENERAL DRIVING CYCLE
Perform the diagnosis only once after engine warm-up.
4. DIAGNOSTIC METHOD
Abnormality Judgment
Judge as NG if the criteria below are met.
Judgment Value
Malfunction Criteria
Maximum output voltage Low side
Minimum output voltage High side
Time Needed for Diagnosis: 200 seconds
Malfunction Indicator Light Illumination: Illuminates when malfunction occurs in two continuous driving
cycles.
Normality Judgment
Judge as OK if the criteria below are met.
Judgment Value
Malfunction Criteria
Maximum output voltage Low side
Minimum output voltage High side
5. DTC CLEAR CONDITION
• When the OK idling cycle is completed 40 times in a row
• When "Clear Memory" is performed
Enable Conditions
≥ 70°C (158°F)
≥ 0.6 V
10 g (0.35 oz)/seconds
or more
> 10.9 V
In operation
5 times or less
Not in limit value
Experienced
Threshold Value
< 550 mV
> 150 mV
Threshold Value
≥ 550 mV
≤ 150 mV
GD(H4DOTC)-73
GENERAL DESCRIPTION