DTC P1152: O2 Sensor Circuit Range/Performance (Low) (Bank1 Sensor1)

OUTLINE OF DIAGNOSIS
Detect that lambda value remains Low.

Judge NG when lambda value is abnormal in accordance with lambda value of front oxygen (A/F) sensor and running condition that is vehicle speed, amount of intake air engine coolant temperature, sub feedback control, etc.

Lambda value = Actual air fuel ratio/Theoretical air fuel ratio

Lambda > 1: Lean

Lambda < 1: Rich
COMPONENT DESCRIPTION

Fig 1: O2 Sensor Circuit Range/Performance Graph
Courtesy of SUBARU OF AMERICA, INC.

ENABLE CONDITION

ENABLE CONDITION CHART

Secondary Parameters	Enable Conditions
All secondary parameters to be in enable conditions	4 seconds or more
Battery voltage	> 10.9 V
Atmospheric pressure	> 75.1 kPa (563 mmHg, 22.2 inHg)
Rear oxygen sensor sub feedback	Operating
Rear oxygen sensor output voltage - feedback target voltage	-0.2 V <--> 0.1 V
or
rear oxygen sensor sub feedback compensation coefficient	On Min.
or
rear oxygen sensor sub feedback compensation coefficient	On Max.
After engine starting	60 seconds or more
Engine coolant temperature	"GREATER THAN EQUAL TO" 75°C (167°F)
Vehicle speed	"GREATER THAN EQUAL TO" 20 km/h (12 MPH)
Amount of intake air	"GREATER THAN EQUAL TO" 6 g/s
Load change during 0.5 engine rev.	"LESS THAN EQUAL TO" 0.01 g/rev
Impedance of front oxygen (A/F) sensor	0 <-- --> 50 Ω
Learning value of evaporation gas density	"LESS THAN EQUAL TO" 0.2
Total time of operating canister purge	20 seconds or more

GENERAL DRIVING CYCLE
Perform the diagnosis continuously at a constant speed of 20 km/h (12 MPH) or more over 60 seconds after vehicle starts to run.

DIAGNOSTIC METHOD

Judge NG when the continuous time of completing the malfunction criteria below becomes more than the time needed for diagnosis (10 seconds). Judge OK and clear NG when the malfunction criteria below are not completed.

Judgment Value

JUDGMENT VALUE CHART

Malfunction Criteria	Threshold Value
Output lambda when rear oxygen sensor sub feedback compensation coefficient being at not high limit	"LESS THAN EQUAL TO" 0.85

Time Needed for Diagnosis: 10 seconds

Malfunction Indicator Light Illumination: Illuminates when malfunction occurs in 2 continuous driving cycles.

DTC CLEAR CONDITION
- When the OK idling cycle was completed 40 times in a row
- When "Clear Memory" was performed
MALFUNCTION INDICATOR LIGHT CLEAR CONDITION
- When the OK driving cycle was completed 3 times in a row
- When "Clear Memory" was performed
FAIL SAFE
- Front oxygen (A/F) sensor main learning correction: Not allowed to calculate
- Correction when re-starting at high temperature: Normally minimum value 0.3 --> 0
- Purge control: Not allowed to purge
ECM OPERATION AT DTC SETTING
Memorize the freeze frame data. (For test mode $02)