Subaru 2009 IMPREZA Service Manual page 1710

Diagnostic Trouble Code (DTC) Detecting Criteria
GENERAL DESCRIPTION
5. DIAGNOSTIC METHOD
Purge control solenoid valve stuck open fault diagnosis
DTC
P0457 Evaporative Emission Control System Leak Detected (Fuel Cap Loose/Off)
Purpose of Mode Z
When performing the leakage diagnosis of EVAP system, the purge control solenoid valve must operate nor-
mally. Therefore, mode Z is used to diagnose the purge control solenoid valve stuck open condition. Note
that if a purge control solenoid valve stuck open fault is detected, the EVAP system leakage diagnosis is can-
celled.
Diagnostic method
Purge control solenoid valve functional diagnosis is performed by monitoring the tank pressure in mode Z.
• Abnormality Judgement
If OK judgement cannot be made, extend Mode Z, and Judge as NG when the following conditions are es-
tablished after predetermined amount of time.
Judgement Value
Malfunction Criteria
evptez – evptezha
evptezini
Time of 2 2 (0.53 US gal, 0.44 Imp gal)
or more fuel no sloshing
Time Needed for Diagnosis: 0 ms + 3000 ms + 13000 ms
Malfunction Indicator Light Illumination: Illuminates when malfunction occurs in 2 continuous driving cy-
cles.
When judgement for purge control solenoid valve stuck open NG is made, end the evaporative diagnosis.
Cancel the evaporative diagnosis when the OK/NG judgement for purge control solenoid valve stuck open
cannot be made in Mode Z.
• Normality Judgement
Judge as OK and change to Mode A when the following conditions are established after predetermined time
has passed since Mode Z started.
Judgement Value
Malfunction Criteria
evptez – evptezha
Threshold Value
> 0.9 kPa (6.5 mmHg, P0457
0.3 inHg)
1.4 kPa (10.7 mmHg,
0.4 inHg)
40000 ms
Threshold Value
0.4 kPa (3 mmHg, P0457
0.1 inHg)
GD(H4DOTC)-122
DTC
DTC