DTC P0139: 1/2 O2 Sensor Slow Response: Notes

NOTE: The 1/2 HO2S may also be referred to as a downstream oxygen sensor. On California vehicles, 1/2 HO2S is located in exhaust pipe behind left catalytic converter. On non-California vehicles, 1/2 HO2S is located in exhaust pipe behind catalytic converter.

NOTE: For circuit identification and wiring diagram, see WIRING DIAGRAMS article. After each repair procedure has been completed, reconnect all components. Perform TEST VER-5: OBD-II MONITOR VERIFICATION under VERIFICATION TESTS to ensure system is functioning properly.