Subaru Impreza 3 / Impreza WRX / Impreza WRX STI. Manual — part 333

GD(H4DOTC)-84

Diagnostic Trouble Code (DTC) Detecting Criteria

GENERAL DESCRIPTION

AU:DTC P0140 O2 SENSOR CIRCUIT NO ACTIVITY DETECTED (BANK1

SENSOR2)

1. OUTLINE OF DIAGNOSIS

Detect the rear oxygen sensor open or short circuit. Judge as NG when the rear oxygen sensor voltage can

be determined to be abnormal considering conditions such as intake air amount, engine coolant tempera-

ture, main feedback control and deceleration fuel cut.

2. COMPONENT DESCRIPTION

3. ENABLE CONDITION (USED ONLY FOR MALFUNCTION JUDGMENT)

4. GENERAL DRIVING CYCLE

Perform the diagnosis once after starting the engine.

(A)

Electromotive force

(B)

Air fuel ratio

(C)

Lean

(D)

Rich

(E)

Theoretical air fuel ratio

(F)

Comparative voltage

(1)

Atmosphere

(2)

Exhaust gas

(3)

Electromotive force

Secondary Parameters

Enable Conditions

Closed loop control at the rear oxygen sensor

In operation

Target output voltage of rear oxygen sensor

≥ 0.55 V + 0.05 V

Amount of intake air

≥ 10 g/s (0.35 oz/s)

Engine coolant temperature

≥ –40 °C (–40 °F)

Misfire detection every 200 rotations

< 65535 time(s)

Front oxygen (A/F) sensor compensation coefficient

Not in limit value

Battery voltage

≥ 10.9 V

Deceleration fuel cut of 5000 ms or more.

Experienced

EN-01696

(3)

V

(1)

(2)

(2)

(E)

(F)

(C)

(B)

(D)

(A)

GD(H4DOTC)-85

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: 90000 ms

Malfunction Indicator Light Illumination: Illuminates when malfunction occurs in 2 continuous driving cy-

cles.
• Normality Judgment
Judge as OK and clear the NG if the following conditions are established.

Time Needed for Diagnosis: Less than 1 second

Judgment Value

Malfunction Criteria

Threshold Value

Minimum output voltage

> 0.15 V

or

Maximum output voltage

< 0.55 V

Judgment Value

Malfunction Criteria

Threshold Value

Diagnosis of the rear oxygen sensor voltage low side

Incomplete

Minimum output voltage

≤ 0.15 V

Maximum output voltage

≥ 0.55 V

GD(H4DOTC)-86

Diagnostic Trouble Code (DTC) Detecting Criteria

GENERAL DESCRIPTION

AV:DTC P0141 O2 SENSOR HEATER CIRCUIT (BANK1 SENSOR2)

1. OUTLINE OF DIAGNOSIS

Detect malfunction of the rear oxygen sensor heater.

Judge as NG if it is determined that the rear oxygen sensor impedance is large by observing the engine con-

ditions.

2. COMPONENT DESCRIPTION

3. ENABLE CONDITIONS

4. GENERAL DRIVING CYCLE

Perform the diagnosis continuously after 1000 ms seconds or more have passed since the engine started.

(1)

Element cover (outer)

(3)

Sensor element

(5)

Sensor housing

(2)

Element cover (inner)

(4)

Ceramic heater

Secondary Parameters

Enable Conditions

Battery voltage

≥ 10.9 V

Elapsed time after starting the engine

≥ 1000 ms

Engine coolant temperature

≥ 70 °C (158 °F)

A/F sensor element impedance

≤ 50 Ω

A/F sensor heater control duty

≤ 75 %

Rear oxygen sensor heater control duty

< 30 %

EN-01683

(1)

(2) (3)

(4)

(5)

GD(H4DOTC)-87

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 × 2500 time(s)

Malfunction Indicator Light Illumination: Illuminates when malfunction occurs in 2 continuous driving cy-

cles.
• 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: 4 ms × 2500 time(s)

Judgment Value

Malfunction Criteria

Threshold Value

Output terminal for heater characteristics failure detection

Low

Judgment Value

Malfunction Criteria

Threshold Value

Output terminal for heater characteristics failure detection

High