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Home › Saturn › 2000 › LS2 Standard › Repair and Diagnosis › Engine Performance › System › Engine Controls - Self-Diagnostics › Diagnostic Tests › DTC P0136: Ho2S Circuit - Bank 1, Sensor 2 › Diagnostic Procedures

Diagnostic Procedures

  1. Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
  2. Operate engine at 1500 RPM for about one minutes. Ensure engine coolant temperature is greater than 140°F (60°C). Using scan tool, monitor HO2S bank 1, sensor 2 voltage. If voltage reading is consistently less than 100 mV, go to next step. If voltage reading is not constantly less than 100 mV, problem is intermittent. See DIAGNOSTIC AIDS .
  3. Turn ignition off. Disconnect HO2S bank 1, sensor 2 harness connector. Turn ignition on, with engine off. Observe HO2S bank 1, sensor 2 on scan tool. If voltage reading is not within 391-491 mV, go to next step. If voltage reading is within 391-491 mV, check HO2S circuit or for a lean condition. Repair as necessary.
  4. Turn ignition off. Check for continuity between ground and HO2S sensor harness connector terminal No. 3 (Tan/White wire), then between HO2S harness connector terminals No. 3 (Tan/White wire) and No. 4 (Purple/White wire). If continuity exists on either circuit, go to next step. If continuity does not exist on either circuit, replace ECM.
  5. Check Tan/White wire between HO2S and ECM for short to ground or for short to Purple/White wire. See WIRING DIAGRAMS article. Repair as necessary.
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