1995 Subaru Legacy Outback, StandardFACTORY OEM SERVICE PROCEDURE

DTC P0130 (FO2_V) - Front Oxygen Sensor (O2S) Circuit Malfunction

NOTE: Refer to illustration for connector and terminal identification. See Figure -Figure .
  1. With appropriate test apparatus, determine CO% content of exhaust gas. If content is less than 2%, go to next step. If CO% content is more than 2%, check for improper fuel and if engine oil or coolant level is extremely low.
  2. Turn ignition to OFF. After Connecting SSM or OBD-II scan tool, start engine. Turn SSM or OBD-II scan tool to ON. Run engine until coolant temperature is above 160°F (70°C). Run engine at 2000-3000 RPM for one minute. Select function mode F14 to read front O2S maximum output signal, or F15 to read O2S minimum output signal. If the voltage difference between F14 and F15 readings is 0.1 volt or less, go to step 3). If the difference is more than 0.1 volt, replace front O2S.
  3. Turn ignition to OFF. Disconnect O2S connector from front O2S. Turn Ignition switch to ON. Measure voltage between O2S connector B18, terminal No. 2 and ground. If voltage is less than 0.2 volt, repair open in harness between ECM and front O2S or poor contact in ECM connector. If voltage is 0.2 volt or more, check for poor contact in front O2S connector and repair as necessary. If contact at connector is okay, replace O2S.
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.