Subaru Legacy IV (2008 year). Manual - part 187

GD(H4SO)-50

Diagnostic Trouble Code (DTC) Detecting Criteria

GENERAL DESCRIPTION

AD:DTC P0133 O2 SENSOR CIRCUIT SLOW RESPONSE (BANK 1 SENSOR 1)

1. OUTLINE OF DIAGNOSIS

Detect the slow response of front oxygen (A/F) sensor.
Front oxygen (A/F) sensor cover has some ventilation holes for exhaust gas. Clogged ventilation holes are
diagnosed.
When the holes are clogged, the A/F output variation becomes slow comparing with the actual A/F variation
because oxygen which reaches the zirconia layer is insufficient. Therefore, if the sensor cover holes are
clogged, the rich to lean judgment in the ECM is delayed when the actual change from rich to lean occurs.
Judge as NG when the actual movement in comparison to the ECM control amount is slow.

(1)

Cover

(2)

Zirconia

(3)

Clogging

EN-01694

(1)

(2)

(3)

GD(H4SO)-51

Diagnostic Trouble Code (DTC) Detecting Criteria

GENERAL DESCRIPTION

2. COMPONENT DESCRIPTION

3. ENABLE CONDITION

4. GENERAL DRIVING CYCLE

Perform diagnosis only once at a constant speed of 10 km/h — 120 km/h (6.2 MPH — 74.6 MPH) 120000 ms
or more after starting the engine.

(A)

Electromotive force

(C)

Lean

(D)

Rich

(B)

Air fuel ratio

 

 

(1)

Atmosphere

(3)

ZrO

2

(4)

Ceramic heater

(2)

Exhaust gas

Secondary Parameters

Enable Conditions

Time needed for all secondary parame-
ters to be in enable conditions

t 1024 ms

Battery voltage

t 10.9 V

Barometric pressure

> 75 kPa (563 mmHg, 
22.2 inHg)

Closed loop control with main feedback

Operation

Front oxygen (A/F) sensor impedance

0 

: — 50 :

Elapsed time after starting the engine

t 120000 ms

Engine coolant temperature

t 75 °C (167 °F)

Engine speed

1000 rpm — 3200 rpm

Vehicle speed

10 km/h — 120 km/h 
(6.2 MPH — 74.6 MPH)

Amount of intake air

10 g/s — 40 g/s 
(0.35 oz/s — 1.41 oz/s)

Engine load

< 0.02 g/rev (0 oz/rev)

Learning value of EVAP conc. during 
purge

< 0.2 

Total time of operating canister purge

t 19.9 s

(1)

(2)

(4)

(2)

(3)

EN-01693

(C)

(B)

(D)

(A)

GD(H4SO)-52

Diagnostic Trouble Code (DTC) Detecting Criteria

GENERAL DESCRIPTION

5. DIAGNOSTIC METHOD

Calculate faf difference every 32ms × 4 , and the 

O value difference. Calculate the diagnosis value after cal-

culating 1640 time(s).

• 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: 32 ms × 4  × 1640 time(s)
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: 32 ms × 4  × 1640 time(s)

Judgement Value

Malfunction Criteria

Threshold Value

parafca = td2faf/td2lmd

> 0.4  (U5 model)
> 0.45  (Other than U5 model)

where,

 

td2faf (N) = td2faf (n–1) + |d2faf (n)|

 

td2lmd (N) = td2lmd (n–1) + |d2lmd (n)|

 

add up to 32 ms × 4  × 1640 time(s).

 

d2faf (n) = (faf (n) – faf (n–1)) – (faf (n–1) 
– faf (n–2))

d2lmd (n) = (lmd (n) – lmd (n–1)) – (lmd 
(n–1) – lmd (n–2))

faf = main feedback compensation coef-
ficient every 128 milliseconds

lmd = output lambda every 128 millisec-
onds

Judgement Value

Malfunction Criteria

Threshold Value

parafca = td2faf/td2lmd

d 0.4  (U5 model)
d 0.45  (Other than U5 model)

where,

 

td2faf (N) = td2faf (n–1) + |d2faf (n)|

 

td2lmd (N) = td2lmd (n–1) + |d2lmd (n)|

 

add up to 32 ms × 4  × 1640 time(s).

 

d2faf (n) = (faf (n) – faf (n–1)) – (faf (n–1) 
– faf (n–2))

d2lmd (n) = (lmd (n) – lmd (n–1)) – (lmd 
(n–1) – lmd (n–2))

faf = main feedback compensation coef-
ficient every 128 milliseconds

lmd = output lambda every 128 millisec-
onds

GD(H4SO)-53

Diagnostic Trouble Code (DTC) Detecting Criteria

GENERAL DESCRIPTION

AE:DTC P0134 O2 SENSOR CIRCUIT NO ACTIVITY DETECTED 

(BANK 1 SENSOR 1)

1. OUTLINE OF DIAGNOSIS

Detect open circuits of the sensor.
Judge as NG when the impedance of the element is large.

2. COMPONENT DESCRIPTION

3. ENABLE CONDITION

4. GENERAL DRIVING CYCLE

Always perform the diagnosis continuously.

(A)

Electromotive force

(C)

Lean

(D)

Rich

(B)

Air fuel ratio

 

 

(1)

Atmosphere

(3)

ZrO

2

(4)

Ceramic heater

(2)

Exhaust gas

Secondary Parameters

Enable Conditions

None

 

(1)

(2)

(4)

(2)

(3)

EN-01693

(C)

(B)

(D)

(A)