DTC P1134: A/F Sensor Micro-Computer Problem

OUTLINE OF DIAGNOSIS
- Detect the malfunction of IC communication.
- Judge NG when the communication to front oxygen (A/F) sensor control IC is unable.
COMPONENT DESCRIPTION

Fig 1: Identifying Front Oxygen (A/F) Sensor And Air Fuel Ratio Graph (DTC P1134)
Courtesy of SUBARU OF AMERICA, INC.

ENABLE CONDITION

Secondary Parameters	Enable Conditions
Battery voltage	"GREATER THAN EQUAL TO" 10.9 V
After engine starting	"GREATER THAN EQUAL TO" 140 seconds

GENERAL DRIVING CYCLE
Perform the diagnosis continuously in 140 seconds after starting the engine.

DIAGNOSTIC METHOD

Abnormality Judgment

Judge NG when the malfunction criteria below are completed.

Judgment Value

JUDGMENT VALUE

Malfunction Criteria	Threshold Value
Communication error to main CPU	"GREATER THAN EQUAL TO" 250 times

Time Needed for Diagnosis: 12.5 seconds

Malfunction Indicator Light Illumination: Illuminates as soon as malfunction occurs.

Normality Judgment

Judge OK and clear the NG when the malfunction criteria below are completed.

Judgment Value

JUDGMENT VALUE

Malfunction Criteria	Threshold Value
Error	None

DTC CLEAR CONDITION
- When the OK idling cycle is completed 40 times in a row
- When "Clear Memory" was performed
MALFUNCTION INDICATOR LIGHT CLEAR CONDITION
- When the OK driving cycle is completed 3 times in a row
- When "Clear Memory" was performed
FAIL SAFE
None
ECM OPERATION AT DTC SETTING
Memorize the freeze frame data. (For test mode $02)