Content .. 611 612 613 614 ..

Subaru Legacy IV (2008 year). Manual - part 613

GD(H6DO)-72

Diagnostic Trouble Code (DTC) Detecting Criteria

GENERAL DESCRIPTION

BA:DTC P0171 SYSTEM TOO LEAN (BANK 1)

1. OUTLINE OF DIAGNOSIS

Detect fuel system malfunction by the amount of main feedback control.

Diagnostic method

Fuel system is diagnosed by comparing the target air fuel ratio calculated by ECM with the actual air fuel ratio
measured by sensor.

2. ENABLE CONDITION

3. GENERAL DRIVING CYCLE

Perform the diagnosis continuously at idling or at a constant speed after warming up the engine.

4. DIAGNOSTIC METHOD

• Abnormality Judgement

Compare the diagnosed value (fsobd) with the threshold value, and if a condition meeting the malfunction cri-
teria below continues for 10 s × 5 time(s) or more, judge that there is a fault in the fuel system.

Time Needed for Diagnosis: 10 s × 5 time(s)
Malfunction Indicator Light Illumination: Illuminates when malfunction occurs in 2 continuous driving cycles.

• 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: 10 s

Secondary Parameters

Enable Conditions

A/F main learning system

In operation

Engine coolant temperature

t 75 °C (167 °F)

Engine load change

< 0.02 g/rev (0 oz/rev)

Engine load

t Value of Map 1

Map1

Engine speed (rpm)

Idling

700

1000

1500

2000

2500

3000

3500

4000

4500

5000

Measured value (g(oz)/rev)

Non-turbo

0.357

(0.01)

0.25

(0.01)

0.25

(0.01)

0.317

(0.01)

0.326

(0.01)

0.337

(0.01)

0.397

(0.01)

0.439

(0.02)

0.454

(0.02)

0.454

(0.02)

Judgement Value

Malfunction criteria

Threshold value

fsobd = (sglmd – tglmda) + faf + flaf

t Value of Map 2

In this case: sglmd = measured lambda

tglmda = target lambda

faf = main feedback compensation coef-
ficient every 64 milliseconds

flaf = main feedback learning compensa-
tion coefficient

Map2

Amount of air (g (oz)/s)

0 (0)

3.2

(0.11)

6.4

(0.23)

9.6

(0.34)

12.8

(0.45)

(0.56)

19.2

(0.68)

fsobdL1 (%)

1.4

1.332

1.265

Judgement Value

Malfunction Criteria

Threshold Value

fsobd = (sglmd – tglmda) + faf + flaf

< 1.2

GD(H6DO)-73

Diagnostic Trouble Code (DTC) Detecting Criteria

GENERAL DESCRIPTION

BB:DTC P0172 SYSTEM TOO RICH (BANK 1)

1. OUTLINE OF DIAGNOSIS

Detect fuel system malfunction by the amount of main feedback control.

Diagnostic method

Fuel system is diagnosed by comparing the target air fuel ratio calculated by ECM with the actual air fuel ratio
measured by sensor.

2. ENABLE CONDITION

3. GENERAL DRIVING CYCLE

Perform the diagnosis continuously at idling or at a constant speed after warming up the engine.

4. DIAGNOSTIC METHOD

• Abnormality Judgement

Time Needed for Diagnosis: 10 s × 5 time(s)
Malfunction Indicator Light Illumination: Illuminates when malfunction occurs in 2 continuous driving cycles.

• Normality Judgement

Judge as OK when the malfunction criteria below continues for 10 seconds.

Time Needed for Diagnosis: 10 s

Secondary Parameters

Enable Conditions

A/F main learning system

In operation

Engine coolant temperature

t 75 °C (167 °F)

Engine load change

d 0.02 g/rev (0 oz/rev)

Learning value of EVAP conc.

< 0.1

Cumulative time of canister purge after engine start

t 20 s

Continuous period after canister purge starting

t 29884 ms

Engine load

t Value of Map 1

Map1

Engine speed (rpm)

Idling

700

1000

1500

2000

2500

3000

3500

4000

4500

5000

Measured value (g(oz)/rev)

Non-turbo

0.357

(0.01)

0.25

(0.01)

0.25

(0.01)

0.317

(0.01)

0.326

(0.01)

0.337

(0.01)

0.397

(0.01)

0.439

(0.02)

0.454

(0.02)

0.454

(0.02)

Judgement Value

Malfunction criteria

Threshold value

fsobd = (sglmd – tglmda) + faf + flaf

< Value of Map 2

In this case: sglmd = measured lambda

tglmda = target lambda

faf = main feedback compensation coefficient every 64 milliseconds

flaf = main feedback learning compensation coefficient

Map2

Amount of air (g (oz)/s)

0 (0)

3.2

(0.11)

6.4

(0.23)

9.6

(0.34)

12.8

(0.45)

(0.56)

19.2

(0.68)

fsobdL1 (%)

0.6

0.688

0.735

Judgement Value

Malfunction Criteria

Threshold Value

fsobd = (sglmd – tglmda) + faf + flaf

t 0.8

GD(H6DO)-74

Diagnostic Trouble Code (DTC) Detecting Criteria

GENERAL DESCRIPTION

BC:DTC P0174 SYSTEM TOO LEAN (BANK 2)

1. OUTLINE OF DIAGNOSIS

NOTE:
For the detection standard, refer to DTC P0171. <Ref. to GD(H6DO)-72, DTC P0171 SYSTEM TOO LEAN
(BANK 1), Diagnostic Trouble Code (DTC) Detecting Criteria.>

BD:DTC P0175 SYSTEM TOO RICH (BANK 2)

1. OUTLINE OF DIAGNOSIS

NOTE:
For the detection standard, refer to DTC P0172. <Ref. to GD(H6DO)-73, DTC P0172 SYSTEM TOO RICH
(BANK 1), Diagnostic Trouble Code (DTC) Detecting Criteria.>

GD(H6DO)-75

Diagnostic Trouble Code (DTC) Detecting Criteria

GENERAL DESCRIPTION

BE:DTC P0181 FUEL TEMPERATURE SENSOR “A” CIRCUIT RANGE/

PERFORMANCE

1. OUTLINE OF DIAGNOSIS

Detect faults in the fuel temperature sensor output properties.
Diagnosis is performed in two methods (drift diagnosis and stuck diagnosis). If either is NG, judge as NG. If
both are OK, Judge as OK and clear the NG.

Drift Diagnosis

Normally fuel temperature is lower than engine coolant temperature. When the fuel temperature becomes
higher than the engine coolant temperature, the range is considered to be shifted, and judged as NG.

Stuck Diagnosis

As the engine warms up (cumulative amount of intake air after starting is large), if the fuel temperature which
should rise does not, determine as being stuck and NG.

2. COMPONENT DESCRIPTION

3. ENABLE CONDITION

DRIFT DIAGNOSIS

4. GENERAL DRIVING CYCLE

Always perform the diagnosis continuously.

(A)

Resistance value (

(B)

Fuel temperature °C (°F)

Secondary Parameters

Enable Conditions

None

EN-01700

(A)

(B)

Content .. 611 612 613 614 ..