Subaru Impreza 3 / Impreza WRX / Impreza WRX STI. Manual - part 318

GD(H4DOTC)-24

Diagnostic Trouble Code (DTC) Detecting Criteria

GENERAL DESCRIPTION

R: DTC P0031 HO2S HEATER CONTROL CIRCUIT LOW (BANK 1 SENSOR 1)

1. OUTLINE OF DIAGNOSIS

Detect front oxygen (A/F) sensor heater open or short circuit.

The front oxygen (A/F) sensor heater performs duty control, and the output terminal voltage at ON is 0 V, and

the output terminal voltage at OFF is the battery voltage.

Judge as NG when the terminal voltage remains Low.

2. COMPONENT DESCRIPTION

3. ENABLE CONDITIONS

4. GENERAL DRIVING CYCLE

Always perform the diagnosis continuously.

(A)

Battery voltage

(B)

Front oxygen (A/F) sensor heater 
output voltage

(C)

128 ms

(D)

Low error

 

 

 

 

Secondary Parameters

Enable Conditions

Battery voltage

≥ 10.9 V

EN-01792

(C)

(A)

(B)

ON

OFF

0V

(D)

GD(H4DOTC)-25

Diagnostic Trouble Code (DTC) Detecting Criteria

GENERAL DESCRIPTION

5. DIAGNOSTIC METHOD

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

Time Needed for Diagnosis: 4 ms × 250 time(s)

Malfunction Indicator Light Illumination: Illuminates as soon as a malfunction occurs.
• Normality Judgment
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

Judgment Value

Malfunction Criteria

Threshold Value

Output voltage level

Low

Front oxygen (A/F) sensor heater control duty

< 87.5 %

Judgment Value

Malfunction Criteria

Threshold Value

Output voltage level

High

GD(H4DOTC)-26

Diagnostic Trouble Code (DTC) Detecting Criteria

GENERAL DESCRIPTION

S: DTC P0032 HO2S HEATER CONTROL CIRCUIT HIGH (BANK 1 SENSOR 1)

1. OUTLINE OF DIAGNOSIS

Detect front oxygen (A/F) sensor heater open or short circuit.

The front oxygen (A/F) sensor heater performs duty control, and the output terminal voltage at ON is 0 V, and

the output terminal voltage at OFF is the battery voltage.

Judge as NG when the terminal voltage remains High.

2. COMPONENT DESCRIPTION

3. ENABLE CONDITIONS

4. GENERAL DRIVING CYCLE

Always perform the diagnosis continuously.

(A)

Battery voltage

(B)

Front oxygen (A/F) sensor heater 
output voltage

(C)

128 ms

(D)

High error

 

 

 

 

Secondary Parameters

Enable Conditions

Battery voltage

≥ 10.9 V

EN-01793

(C)

(A)

(B)

ON

OFF

0V

(D)

GD(H4DOTC)-27

Diagnostic Trouble Code (DTC) Detecting Criteria

GENERAL DESCRIPTION

5. DIAGNOSTIC METHOD

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

Time Needed for Diagnosis: 4 ms × 500 time(s)

Malfunction Indicator Light Illumination: Illuminates as soon as a malfunction occurs.
• Normality Judgment
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

Judgment Value

Malfunction Criteria

Threshold Value

Output voltage level

High

Front oxygen (A/F) sensor heater control duty

≥ 12.5 %

Judgment Value

Malfunction Criteria

Threshold Value

Output voltage level

Low