DTC P0134: O2 Sensor Circuit No Activity Detected (Bank 1 Sensor 1)

OUTLINE OF DIAGNOSIS
Detect the open circuit of front oxygen (A/F) sensor.

Diagnosis is performed using A/F microcomputer, and communication is established between A/F microcomputer and main microcomputer. Judge NG when the data of open circuit NG is transmitted.
COMPONENT DESCRIPTION

Fig 1: A/F Sensor Cross Sectional View And Air Fuel Ratio Graph
Courtesy of SUBARU OF AMERICA, INC.

ENABLE CONDITION

ENABLE CONDITIONS

Secondary Parameters	Enable Conditions
None

GENERAL DRIVING CYCLE
Terminate the diagnosis if the open circuit, low voltage short circuit or high voltage short circuit becomes NG once by performing diagnosis continuously.

DIAGNOSTIC METHOD

Judge NG when the continuous time of completing the malfunction criteria below becomes more than 5 seconds.

Judgment Value

JUDGMENT VALUE

Malfunction Criteria	Threshold Value
Heater control	In operation
Resistance of front oxygen (A/F) sensor	500 Ω

Time Needed for diagnosis: 5 seconds

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

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
None
ECM OPERATION AT DTC SETTING
Memorize the freeze frame data. (For test mode $02)