Subaru Legacy IV (2008 year). Manual - part 431

GD(H4DOTC)-174

Diagnostic Trouble Code (DTC) Detecting Criteria

GENERAL DESCRIPTION

CS:DTC P1410 SECONDARY AIR INJECTION SYSTEM SWITCHING VALVE 

STUCK OPEN

1. OUTLINE OF DIAGNOSIS

Always detect abnormally that both combination valve electromagnetic valve and the reed valve are open
failure.
Calculate the integrated value of Max./Min. value and output voltage deviation of the secondary air delivery
pipe pressure sensor output voltage in a given time after engine start. Judge as NG if the integrated value
and the difference between Max. and Min. values are large.

2. ENABLE CONDITIONS

3. GENERAL DRIVING CYCLE

Perform continuous diagnosis when air flow amount is large during the secondary air pump stop after engine
start.

Secondary Parameters

Enable Conditions

Engine speed

t 500 rpm

 and

 

< 10000 rpm

Elapsed time after starting the engine

t 9000 ms

After secondary air system stops

t 9000 ms

Amount of intake air

t 2 g/s (0.07 oz/s)

 and

 

< 400 g/s (14.11 oz/s)

Battery voltage

t 10.9 V

Engine load

> 0 g/rev

After fuel cut

t 1000 ms

GD(H4DOTC)-175

Diagnostic Trouble Code (DTC) Detecting Criteria

GENERAL DESCRIPTION

4. DIAGNOSTIC METHOD

When both combination valve electromagnetic valve and the reed valve are open failure, the failure appears
as pulses in the secondary air delivery pipe pressure sensor output. Detect abnormality by capturing these
pulses using the following method.

• Abnormality Judgement

Calculate Max./Min. value of the secondary air delivery pipe pressure sensor output voltage and the sum of
the output voltage deviation for the given time. Compare the difference between Max. and Min. values with
threshold value and also compare the sum value with the threshold value. If both values exceed the threshold
value, count up NG counter and then judge as NG if the counter reaches the given times.

Time Needed for Diagnosis: 2000 ms × 20 time(s)
Malfunction Indicator Light Illumination: Illuminates as soon as a malfunction occurs.

• Normality Judgement

Judge as OK and clear NG if neither exceeds the threshold value, or if either of the two exceeds the threshold
value.

Time Needed for Diagnosis: 2000 ms

Judgement Value

Malfunction Criteria

Threshold Value

Pipe inner pressure difference between 
Max. and Min.

> 0.05 V

Sum of the pipe inner pressure variation 
value every 4 milliseconds

> 5 V

Barometric pressure variation value

< 26.7 kPa (200 mmHg, 
7.9 inHg)

Judgement Value

Malfunction Criteria

Threshold Value

Pipe inner pressure difference between 
Max. and Min.

d 0.05 V

Sum of the pipe inner pressure variation 
value every 4 milliseconds

d 5 V

GD(H4DOTC)-176

Diagnostic Trouble Code (DTC) Detecting Criteria

GENERAL DESCRIPTION

CT:DTC P1418 SECONDARY AIR INJECTION SYSTEM CONTROL “A” CIRCUIT 

SHORTED

1. OUTLINE OF DIAGNOSIS

Judge as NG when the ECM output level differs from the actual terminal level.

2. ENABLE CONDITIONS

3. GENERAL DRIVING CYCLE

Always perform the diagnosis continuously.

4. 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

Secondary Parameters

Enable Conditions

None

 

Judgement Value

Malfunction Criteria

Threshold Value

Battery voltage

t 10.9 V

Ignition

ON

Terminal output voltage when ECM out-
puts ON signal

HIGH

Judgement Value

Malfunction Criteria

Threshold Value

Battery voltage

t 10.9 V

Ignition

ON

Terminal output voltage when ECM out-
puts ON signal

LOW

GD(H4DOTC)-177

Diagnostic Trouble Code (DTC) Detecting Criteria

GENERAL DESCRIPTION

CU:DTC P1420 FUEL TANK PRESSURE CONTROL SOL. VALVE CIRCUIT HIGH

1. OUTLINE OF DIAGNOSIS

Detect the open/short circuit of pressure control solenoid valve.
Judge as NG when ECM output level is different from actual terminal level.

2. COMPONENT DESCRIPTION

3. ENABLE CONDITION

4. GENERAL DRIVING CYCLE

Always perform the diagnosis after starting the engine.

(A)

Barometric pressure

(B)

Shut-off valve

(C)

To fuel tank

(1)

Filter

(3)

Connector terminal

(5)

Valve

(2)

Coil

(4)

Diaphragm

Secondary Parameters

Enable Conditions

None

 

EN-01759

(1)

(2)

(3)

(4)

(5)

(A)

(B)

(C)