Subaru Legacy IV (2008 year). Manual - part 423

GD(H4DOTC)-142

Diagnostic Trouble Code (DTC) Detecting Criteria

GENERAL DESCRIPTION

BX:DTC P0463 FUEL LEVEL SENSOR “A” CIRCUIT HIGH

1. OUTLINE OF DIAGNOSIS

Detect the open or short circuit of fuel level sensor. Judge as NG if out of specification.

2. COMPONENT DESCRIPTION

3. ENABLE CONDITION

4. GENERAL DRIVING CYCLE

Always perform the diagnosis continuously.

(1)

Engine control module (ECM)

(3)

Fuel sub level sensor

(4)

Detecting circuit

(2)

Fuel level sensor

(5)

Body integrated unit

 

 

Secondary Parameters

Enable Conditions

None

 

(5)

(4)

(1)

(2)

(3)

EN-05371

GD(H4DOTC)-143

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: 1000 ms
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

Battery voltage

t 10.9 V

Elapsed time after starting the engine

t 3000 ms

Output voltage

t 7.212 V

Judgement Value

Malfunction Criteria

Threshold Value

Battery voltage

t 10.9 V

Elapsed time after starting the engine

t 3000 ms

Output voltage

< 7.212 V

GD(H4DOTC)-144

Diagnostic Trouble Code (DTC) Detecting Criteria

GENERAL DESCRIPTION

BY:DTC P0464 FUEL LEVEL SENSOR CIRCUIT INTERMITTENT

1. OUTLINE OF DIAGNOSIS

Detect the unstable output faults from the fuel level sensor caused by noise. Judge as NG when the max. val-
ue and cumulative value of output voltage variation of the fuel level sensor is larger than the threshold value.

2. ENABLE CONDITION

3. GENERAL DRIVING CYCLE

• Always perform the diagnosis continuously at idle speed.
• Pay attention to the fuel level.

Malfunction Criteria

Threshold Value

Engine speed

t 500 rpm

Elapsed time after starting the engine

t 1 second

Battery voltage

t 10.9 V

Idle switch

ON

Fuel level

t 9.6 

2 (2.54 US gal, 

2.11 Imp gal)

 and

 < 

54.4 

2 (14.37 US gal, 

11.97 Imp gal)

Vehicle speed = 0 km/h (0 MPH)

t 10000 ms

GD(H4DOTC)-145

Diagnostic Trouble Code (DTC) Detecting Criteria

GENERAL DESCRIPTION

4. DIAGNOSTIC METHOD

Calculate the Max. value (DELFLMAX) and cumulative value (SUMFL) of output voltage variation of fuel level
sensor during 12.2 seconds. Judge it normal when both max. and cumulative values are not over the thresh-
old value. Otherwise, when either of them is over the threshold value, the diagnosis counter counts up. Judge
as NG if the counter indicated 4 time(s).

(A)

12288 ms

(C)

Malfunction

(D)

Normal

(B)

NG at 4 time(s)

 

 

 

 

Diagnosis condition

Diagnosis timer

(A)

Fuel level sensor
A/D value

Amount of Fuel level
output voltage variation

Diagnosis counter

(B)

Calculate the Max. value (DELFLMAX) 
and the cumulative value (SUMFL).

1

2

3

4

5

6

0

(C)

(D)

EN-05569