DTC P0136: Rear Oxygen Sensor (O2S) Circuit Malfunction
- Turn ignition off. Connect scan tool. Check for DTCs. If DTC P1130 and/or P1131 also exist, go to next step. If DTC P0136 is only DTC set, go to step 3.
- Perform step 1)
of appropriate DTC P1130 or DTC P1131 diagnostic routine. If DTC P1130 or P1131 failed because of problem in fuel system, repair fuel system as necessary. Clear DTCs and retest. Further inspection of DTC P0136 is not necessary. If the failure is not in fuel system, go to next step.
- Start engine and warm to operating temperature above 160°F (70°C). Operate engine at 2000-3000 RPM for 2 minutes. Observe rear O2S output signal. If indicated value fluctuates, go to step 7. If indicated value does not fluctuate, go to next step.
- If rear O2S output is fixed between .2 and .4 volt, go to next step. If value is not fixed between .2 and .4 volt, replace rear O2S.
- Turn ignition off. Disconnect ECM connector B136 (30-pin connector) and rear O2S connectors. Using an ohmmeter, measure resistance between ECM connector B136 (30-pin connector) terminal No. 16 and rear O2S connector terminal No. 3. See Figure and Fig 1
. If resistance is more than 3 ohms, repair open in wiring between ECM and rear O2S connectors. See appropriate wiring diagram in WIRING DIAGRAMS
article. If resistance is 3 ohms or less, go to next step.
Courtesy of SUBARU OF AMERICA, INC.
- Reconnect ECM connector B136 (30-pin connector). Turn ignition on. Using a voltmeter connected to ground, measure voltage between rear O2S connector terminal No. 4 and ground. If voltage is more than .2 volt, replace rear O2S. If voltage is .2 volt or less, repair open in wiring or poor contact between ECM and rear O2S connectors.
- Check for poor O2S installation, exhaust system leaks ahead of rear O2S or loose O2S. Repair as needed. If no problems were found, replace rear O2S.