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Home >> Saturn >> 2001 >> L100 Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P0134: O2S1 Circuit - Insufficient Activity >> Diagnostic Procedures
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Diagnostic Procedures

  1. Operate engine at 1500 RPM for one minute. Ensure engine coolant temperature is more than 158°F (70°C). Using scan tool, monitor O2S1 voltage. If voltage reading is 399-499 millivolts, go to next step. If voltage reading is not 399-499 millivolts, problem is intermittent. See DIAGNOSTIC AIDS .
  2. Disconnect O2S1 harness connector. See Figure. Turn ignition on, engine off. Using a jumper wire, jumper O2S1 harness connector terminal "B" (Purple wire) to ground. Observe scan tool reading. If voltage reading is less than 50 millivolts, go to next step. If voltage reading is not less than 50 millivolts, check for open in circuit or loose connection. Repair as necessary. If circuit and terminals are okay, replace PCM.
  3. Disconnect jumper from ground. Connect jumper between O2S1 harness connectors "A" (Tan wire) and "B" (Purple wire). Observe scan tool reading. If voltage reading is less than 52 millivolts, go to next step. If voltage is not less than 52 millivolts, check for open in Purple wire between O2S1 and PCM. If Purple wire is okay, replace PCM.
  4. Connect jumper wire between O2S1 connector terminals. Observe scan tool reading. If voltage reading is less than 52 millivolts, replace O2S1 sensor. If voltage reading is not less than 52 millivolts, check for open in Tan wire between O2S1 sensor and PCM. If Tan wire is okay, replace PCM.
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