Subaru IMPREZA GD 2007 Series Manual page 2206

asieps_tobira_IM_US.book 139 ページ ２０１２年１月１７日 火曜日 午後３時４８分
Diagnostic Trouble Code (DTC) Detecting Criteria
Diagnostic method
• The diagnostic method consists of creating a sealed vacuum in the fuel tank and then determining the
presence of leakage from the speed at which the tank internal pressure returns to barometric pressure.
• The diagnosis is divided into the following five phases.
Mode A: (Estimated evaporation gas amount)
Calculate the tank pressure change amount (P1) when using mode A. After calculating P1, switch to mode B.
Mode B: (Negative pressure sealed)
Introduce negative pressure in the intake manifold to the tank.
Approximately 0 → –1.4 kPa (0 → –10.5 mmHg, 0 → –0.41 inHg)
When the pressure above (desired negative pressure) is reached, enters Mode C.
In this case, if the tank pressure does not reach the target negative pressure, judge that there is a large leak-
age (10 seconds or 25 seconds) in the system and terminate the evaporative emission control system diag-
nosis.
Abnormality Judgment
Judge as NG (large leak) when the criteria below are met.
Judgment Value
Malfunction Criteria
Time to reach target negative pressure
Or mode B time
(Min. pressure value in tank when in
mode B) – (Tank pressure when mode B
started)
Mode C: (Check pressure rise)
Stop the introduction of negative pressure. (Wait until the tank pressure returns to the start level of P2 cal-
culation.)
Change to Mode D when the tank pressure returns to the start level of P2 calculation.
Judge immediate OK and perform purge control solenoid valve 2 stuck close diagnosis when it does not re-
turn after the specified time passed.
Tank pressure when starting cal-
culation of P2
–1.3 kPa (–9.75 mmHg, –0.38
inHg)
Purge control solenoid valve 2 stuck close diagnosis
Perform purge control solenoid valve 2 stuck close diagnosis using the variation gap between the tank pres-
sure at the end of mode C and after mode C.
Judgment Value
Malfunction Criteria
Tank pressure variation after the end of
mode C
Threshold Value
≥ 25 seconds
≥ 10 seconds
< –0.5 kPa (–4 mmHg,
–0.016 inHg)
Time for advanced OK
judgment
15 seconds
Threshold Value
3.5 seconds
< 0.101 kPa (0.758
mmHg, 0.0298 inHg)
GD(STI)-139
GENERAL DESCRIPTION
DTC
P0457
DTC
P0441