Subaru IMPREZA GD 2007 Series Manual page 1852

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Diagnostic Trouble Code (DTC) Detecting Criteria
3. ENABLE CONDITION
Secondary Parameters
Time needed for all secondary parame-
ters to be in enable conditions
Battery voltage
Atmospheric pressure
Closed loop control with main feedback
Front oxygen (A/F) sensor impedance
After engine starting
Engine coolant temperature
Engine speed
Vehicle speed
Amount of intake air
Engine load change during 0.5 engine
revs.
Learning value of EVAP conc. during
purge
Total time of operating canister purge
4. GENERAL DRIVING CYCLE
Perform diagnosis only once at a constant speed of 10 to 120 km/h (6 to 75 MPH) 120 seconds or more after
starting the engine.
5. DIAGNOSTIC METHOD
Calculate faf difference every 128 milliseconds, and the λvalue difference. Calculate the diagnosis value af-
ter calculating 1,640 times (210 seconds).
Judge as NG if the criteria below are met. Judge as OK and clear the NG when the malfunction criteria below
are not met.
Judgment Value
Malfunction Criteria
parafca = td2faf/td2lmd
where,
td2faf (N) = td2faf (n–1) + |d2faf (n)|
td2lmd (N) = td2lmd (n–1) + |d2lmd (n)|
add up to a total of 210 seconds
d2faf (n) = (faf (n) – faf (n–1)) – (faf (n–1)
– faf (n–2))
d2lmd (n) = (lmd (n) – lmd (n–1)) – (lmd
(n–1) – lmd (n–2))
faf = main feedback compensation coef-
ficient every 128 milliseconds
lmd = output lambda every 128 millisec-
onds
Time Needed for Diagnosis: 210 seconds
Malfunction Indicator Light Illumination: Illuminates when malfunction occurs in two continuous driving
cycles.
6. DTC CLEAR CONDITION
• When the OK idling cycle is completed 40 times in a row
• When "Clear Memory" is performed
Enable Conditions
≥ 1 second
> 10.9 V
> 75.0 kPa (563
mmHg, 22.2 inHg)
Operation
0 ←→ 50 Ω
120 seconds or more
≥ 70°C (158°F)
1,000 ←→ 3,200 rpm
10 ←→ 120 km/h (6
←→ 75 MPH)
10 ←→ 31 g/s (1.32
←→ 4.1 2b/m)
≤ 0.02 g (0.001 oz)/rev
≤ 0.2
20 seconds or more
Threshold Value
≥ 0.392
GD(H4DOTC)-61
GENERAL DESCRIPTION