Subaru Legacy IV (2008 year). Manual - part 419

GD(H4DOTC)-126

Diagnostic Trouble Code (DTC) Detecting Criteria

GENERAL DESCRIPTION

BN:DTC P0448 EVAPORATIVE EMISSION CONTROL SYSTEM VENT CONTROL 

CIRCUIT SHORTED

1. OUTLINE OF DIAGNOSIS

Detect open or short circuit of the drain valve.
Judge as NG when the ECM output level differs from the actual terminal level.

2. COMPONENT DESCRIPTION

3. ENABLE CONDITION

4. GENERAL DRIVING CYCLE

Always perform the diagnosis continuously.

(1)

Bobbin

(8)

Magnetic plate

(14)

Retainer

(2)

Coil

(9)

Shaft

(15)

Diaphragm

(3)

Diode

(10)

Plate

(16)

Movable core

(4)

Stator core

(11)

Valve

(17)

Spring

(5)

End plate

(12)

Housing

(18)

Cover

(6)

Body

(13)

Filter

(19)

O-ring

(7)

Yoke

Secondary Parameters

Enable Conditions

None

 

EN-02294

( 1 )

( 2 )

( 3 )

( 4 )

( 5 )

( 6 )

( 7 )

( 8 )

( 9 )

(10)

(11)

(12)

(13)

(17)

(14)

(15)

(16)

(18)

(19)

(19)

GD(H4DOTC)-127

Diagnostic Trouble Code (DTC) Detecting Criteria

GENERAL DESCRIPTION

5. DIAGNOSTIC METHOD

• Abnormality Judgement

If the duration of time while the following conditions are met is longer than the time indicated, judge as NG.

Time Needed for Diagnosis: 2500 ms
Malfunction Indicator Light Illumination: Illuminates as soon as a malfunction occurs.

• Normality Judgement

Judge as OK and clear the NG if the continuous time while the following conditions are established is more
than the predetermined time.

Time Needed for Diagnosis: Less than 1 second

Judgement Value

Malfunction Criteria

Threshold Value

Battery voltage

t 10.9 V

Elapsed time after starting the engine

t 1 second

Terminal output voltage when ECM out-
puts ON signal

High

Judgement Value

Malfunction Criteria

Threshold Value

Battery voltage

t 10.9 V

Elapsed time after starting the engine

t 1 second

Terminal output voltage when ECM out-
puts ON signal

Low

GD(H4DOTC)-128

Diagnostic Trouble Code (DTC) Detecting Criteria

GENERAL DESCRIPTION

BO:DTC P0451 EVAPORATIVE EMISSION CONTROL SYSTEM PRESSURE 

SENSOR

1. OUTLINE OF DIAGNOSIS

Detect the tank pressure sensor output property abnormality.
Judge as NG when there is no pressure variation, which should exist in the tank, considering the engine sta-
tus.

2. COMPONENT DESCRIPTION

3. ENABLE CONDITION

4. GENERAL DRIVING CYCLE

• Perform the diagnosis continuously after 60 s have passed since the engine started.
• Pay attention to the fuel level and temperature.

(A)

Output voltage

(B)

Input voltage

(C)

To fuel tank

(1)

Connector

(2)

Terminals

Secondary Parameters

Enable Conditions

Elapsed time after starting the engine

t 60 s

Fuel level

t 9.6 

2 (2.54 US gal, 

2.11 Imp gal)

Fuel temperature

< 35 °C (95 °F)

Battery voltage

t 10.9 V

Barometric pressure

t 75 kPa (563 mmHg, 
22.2 inHg)

EN-04462

(A)

(B)

(2)

(1)

(C)

GD(H4DOTC)-129

Diagnostic Trouble Code (DTC) Detecting Criteria

GENERAL DESCRIPTION

5. DIAGNOSTIC METHOD

• Abnormality Judgement

If the duration of time while the following conditions are met is longer than the time indicated, judge as NG.

If the difference between the Max. fuel level every 60 s and Min. fuel level every 60 s is less than 2 

2 (0.53

US gal, 0.44 Imp gal), extend 60 s and make judgement with the Max. and Min. values for the fuel level in 60
s × 2. 60 s If a difference does not appear, extend the time (60 s × 3, 60 s × 4, 60 s × 5) and continue the
judgement. If the difference between the Max. fuel level every 60 s and Min. fuel level every 60 s is 2 

2 (0.53

US gal, 0.44 Imp gal) or more, the diagnosis counter counts up.
Time Needed for Diagnosis: 60 s × 16 time(s) or more
Malfunction Indicator Light Illumination:  Illuminates when malfunction occurs in 2 continuous driving cy-
cles.

• Normality Judgement

Judge as OK and clear the NG if the continuous time while the following conditions are established is more
than the predetermined time.

Time Needed for Diagnosis: Less than 1 second

Judgement Value

Malfunction Criteria

Threshold Value

Number of times that the difference 
between the Max. fuel level every 60 s 
and Min. fuel level every 60 s is 2 

2

(0.53 US gal, 0.44 Imp gal) or more (with 
enable condition established)

t 16 time(s)

Maximum – Minimum tank pressure 
(with enable condition completed)

< 0 kPa (0.375 mmHg, 
0 inHg)

Maximum – Minimum fuel temperature 
(with enable condition completed)

t 7 °C (44.6 °F)

Judgement Value

Malfunction Criteria

Threshold Value

Maximum — Minimum tank pressure

t 0 kPa (0.375 mmHg, 
0 inHg)