1995 Subaru Legacy BaseFACTORY OEM SERVICE PROCEDURE

DTC P0136 (RO2_V) - Rear Oxygen Sensor (O2S) Circuit Malfunction

NOTE: Refer to illustration for connector and terminal identification. See Figure -Figure .
  1. Turn ignition to OFF. After Connecting SSM or OBD-II scan tool, turn ignition to ON. Turn SSM or OBD-II scan tool to ON. If DTC P0130 is also displayed, go to step 2). If DTC P0130 is not displayed, go to step 3).
  2. Perform  step 1) of DTC P0130 . If the failure cause of P0130 is in the fuel system, check the fuel system and repair as necessary. Further inspection of P0136 is not necessary. If the failure is not in the fuel system, go to step 3).
  3. Turn ignition to OFF. After connecting SSM or OBD-II scan tool, start engine. Turn SSM or OBD-II scan tool to ON. Warm engine until coolant temperature is above 160°F (70°C) and maintain 2000-3000 RPM for 2 minutes. On SSM, select function mode F16 to read rear O2S output signal. If indicated data fluctuates, go to step 5). If indicated data is fixed at 0.2-0.4 volt, go to next step.
  4. Measure voltage between rear O2S harness connector T6, terminal No, 4 and ground. If voltage is 0.2 volt or more, replace rear O2S. If voltage is less than 0.2 volt, repair open in harness between rear O2S and ECM, poor contact in rear O2S connector, poor contact in ECM connector or poor contact in rear O2S connecting harness connector.
  5. Check for the following items in the exhaust system:
    • Looseness of installation components
    • Damage to parts (cracks, holes, etc.)
    • Looseness or opening of parts between front and rear O2S.

    Replace or repair defective parts. If no defects, replace rear O2S.

Chapter Navigation
Return to Chapter: Diagnostic Code Testing
Factory Service Tools

Use the Manual With the Right Hardware

Pair factory procedures with proven DIY tools so the instructions are easier to execute.

Disclosure: Verified tool recommendations may earn an affiliate commission at no cost to you.

Shop Manual-Ready ToolsCompare Repair QuoteQuote Shield Pro

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.