DTC P1155 O2 Sensor Circuit Range/Performance (High) (Bank 2 Sensor 1)

DTC DETECTING CONDITION:

Detected when two consecutive driving cycles with fault occur.
GENERAL DESCRIPTION < Refer to DTC P1155 O2 SENSOR CIRCUIT RANGE/PERFORMANCE (HIGH) (BANK 2 SENSOR 1) , Diagnostic Trouble Code (DTC) Detecting Criteria. >

CAUTION: After repair or replacement of faulty parts, perform Clear Memory Mode < Refer to OPERATION , CLEAR MEMORY MODE > and Inspection Mode < Refer to PROCEDURE , INSPECTION MODE >.

WIRING DIAGRAM:

Fig 1: Heated Front Oxygen Sensor - Wiring Diagram

Courtesy of SUBARU OF AMERICA, INC.

DIAGNOSTIC CHART

Step	Check	Yes	No
1 CHECK ANY OTHER DTC ON DISPLAY.	Is any other DTC displayed?	Inspect the relevant DTC using "List of Diagnostic Trouble Code (DTC)". < Refer to LIST OF DIAGNOSTIC TROUBLE CODE (DTC) . >	Go to step 2.
2 CHECK FRONT OXYGEN (A/F) SENSOR DATA. Start the engine. While observing the Subaru Select Monitor or general scan tool screen, warm-up the engine until engine coolant temperature is above 75°C (167°F). If the engine is already warmed-up, operate at idle speed for at least 1 minute. Read data of front oxygen (A/F) sensor signal using the Subaru Select Monitor or general scan tool. NOTE: Subaru Select Monitor For detailed operation procedures, refer to "READ CURRENT DATA FOR ENGINE". < Refer to SUBARU SELECT MONITOR . > General scan tool For detailed operation procedure, refer to the general scan tool operation manual.	Is the measured value within 0.86 - 1.15 at idle?	Go to step 3.	Go to step 4.
3 CHECK REAR OXYGEN SENSOR SIGNAL. Race engine at speeds from idling to 5,000 rpm for a total of 5 cycles. NOTE: To increase engine speed to 5,000 rpm, slowly depress accelerator pedal, taking approximately 5 seconds, and quickly release accelerator pedal to decrease engine speed. Operate the LED operation mode for engine. NOTE: Subaru Select Monitor For detailed operation procedure, refer to the "LED OPERATION MODE FOR ENGINE". < Refer to SUBARU SELECT MONITOR . >	Does the LED of {Rear O2 Rich Signal) blink?	Check front oxygen (A/F) sensor circuit.	Check rear oxygen sensor circuit. < Refer to REAR OXYGEN SENSOR . >
4 CHECK EXHAUST SYSTEM. Check exhaust system parts. NOTE: Check the following items. Looseness of part installation Damage (crack, hole etc.) of parts Looseness of the front oxygen (A/F) sensor Looseness or ill fitting of parts between front oxygen (A/F) sensor and rear oxygen sensor	Is there any fault in exhaust system?	Repair or replace faulty parts.	Replace the front oxygen (A/F) sensor. < Refer to FRONT OXYGEN (A/F) SENSOR . >