Home/Subaru/Forester/Subaru Forester SF (1997-2000)/Repair manual/Testing & Diagnostics/DTC P0139 (RO2_R): REAR O2S CIRCUIT SLOW RESPONSE
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DTC P0139 (RO2_R): REAR O2S CIRCUIT SLOW RESPONSE Subaru Forester SF

If DTC P0136 exists, diagnose DTC P0136 first. Clear DTCs and retest. If DTC P0139 is only code set, replace rear O2S and retest system.