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Home >> Saturn >> 2000 >> LS2 Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P0156: Ho2S Circuit - Bank 2, 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 2, sensor 2 voltage. If voltage reading is consistently less the 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 2, sensor 2 harness connector. Turn ignition on, with engine off. Observe HO2S bank 2, 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 (Gray wire), then between HO2S harness connector terminals No. 3 (Gray wire) and No. 4 (Tan wire). If continuity exists on either circuit, go to next step. If continuity does not exist on either circuit, replace ECM.
  5. Check Gray wire between HO2S and ECM for short to ground or shorted to Tan wire. See WIRING DIAGRAMS article. Repair as necessary.
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