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Home >> Subaru >> 2001 >> Outback Base, Standard >> Repair and Diagnosis >> Engine Performance >> Testing & Diagnosis >> Engine Controls - Self-Diagnostics - 2.2L & 2.5L >> Diagnostic Tests >> DTC P1131: Front Ho2S Circuit Malfunction (Short Circuit) - IMPREZA 2.2L, Legacy & Outback 2.5L M/T & Outback Sport

DTC P1131: Front Ho2S Circuit Malfunction (Short Circuit) - IMPREZA 2.2L, Legacy & Outback 2.5L M/T & Outback Sport

  1. Perform basic diagnostic procedure. See BASIC DIAGNOSTIC PROCEDURE . Turn ignition off. Disconnect ECM connector B136 (30-pin connector). Using an ohmmeter, measure resistance between ground and ECM connector B136 (30-pin connector) terminal No. 7. See Figure. If resistance is more than 10 ohms, go to next step. If resistance is not more than 10 ohms, locate and repair short to ground in wiring between ECM and front HO2S. See WIRING DIAGRAMS article.
  2. Measure resistance between ground and ECM connector B136 (30-pin connector) terminal No. 20. If resistance is more than 10 ohms, go to next step. If resistance is not more than 10 ohms, locate and repair short to ground in wiring between ECM and front HO2S.
  3. Reconnect ECM connector B136 (30-pin connector). Turn ignition on. Using DVOM connected to ground, backprobe ECM connector B136 (30-pin connector) terminal No. 7. If voltage is more than 4.5 volts, go to next step. If voltage is not more than 4.5 volts, go to step  5.
  4. Using DVOM connected to ground, backprobe ECM connector B136 (30-pin connector) terminal No. 7. If voltage is more than 10 volts, locate and repair short to voltage in wiring between ECM and front HO2S. After repair, replace ECM. If voltage is not more than 10 volts, check for poor terminal contact at ECM connector.
  5. Measure voltage between ground and ECM connector B136 (30-pin connector) terminal No. 20. If voltage is more than 4.95 volts, go to next step. If voltage is not more than 4.95 volts, replace front HO2S.
  6. Measure voltage between ground and ECM connector B136 (30-pin connector) terminal No. 20. If voltage is more than 10 volts, locate and repair short to voltage in wiring between ECM and front HO2S. After repair, replace ECM. If voltage is not more than 10 volts, check for poor terminal contact at ECM connector. Clear memory and perform verification procedure. See CLEARING DIAGNOSTIC TROUBLE CODES  and VERIFICATION PROCEDURE  .
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