Wiring Diagram:

Fig 1: DTC P0133 - O2 Sensor Circuit Slow Response (Bank 1 Sensor 1)-

Courtesy of SUBARU OF AMERICA, INC.

DIAGNOSTIC STEPS DTC P0133

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)". < Ref. to , LIST OF DIAGNOSTIC TROUBLE CODE (DTC) . > NOTE: In this case, it is not necessary to inspect DTC P0133.	Go to step 2.
2. CHECK EXHAUST SYSTEM. NOTE: Check the following items. Loose installation of front portion of exhaust pipe onto cylinder heads Loose connection between front exhaust pipe and front catalytic converter Damage of exhaust pipe resulting in a hole	Is there any malfunction in exhaust system?	Repair exhaust system.	Replace front oxygen (A/F) sensor. Ref. to FRONT OXYGEN (A/F) SENSOR .