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

Fig 1: O2 Sensor Circuit Range/Performance (High) (Bank 2 Sensor 1) - Wiring Diagram

Courtesy of SUBARU OF AMERICA, INC.

DIAGNOSIS PROCEDURE

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) .	Go to step 2 .
2 CHECK FRONT OXYGEN (A/F) SENSOR CONNECTOR, REAR OXYGEN SENSOR CONNECTOR AND COUPLING CONNECTOR.	Has water entered the connector?	Completely remove any water inside.	Go to step 3 .
3 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 the signal data of the front oxygen (A/F) sensor using the Subaru Select Monitor or general scan tool. NOTE: Subaru Select Monitor For detailed operation procedures, refer to "READ CURRENT DATA FOR ENGINE". <Ref. 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 4 .	Go to step 5 .
4 CHECK REAR OXYGEN SENSOR SIGNAL. Race engine at speeds from idling to 3,000 rpm for a total of 5 cycles. NOTE: To increase engine speed to 3,000 rpm, slowly depress accelerator pedal, taking approximately 5 seconds, and quickly release accelerator pedal to decrease engine speed. Using the Subaru Select Monitor, execute the engine LED operation mode process. NOTE: For the detailed operation procedure, refer to the "LED OPERATION MODE FOR ENGINE". <Ref. 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. <Ref. to REAR OXYGEN SENSOR . >
5 CHECK EXHAUST SYSTEM. Check exhaust system parts. NOTE: Check the following items: Loosening of part attachment Damage (cracks, holes etc.) of parts Loosening of front oxygen (A/F) sensor Loose or improperly attached parts between the front oxygen (A/F) sensor to rear oxygen sensor	Is there any fault in exhaust system?	Repair or replace faulty parts.	Replace the front oxygen (A/F) sensor. <Ref. to FRONT OXYGEN (A/F) SENSOR . >