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Home >> Saturn >> 2002 >> SL2 Automatic, MP6 >> 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. Start and operate engine at 1500 RPM for about one minute. Ensure engine coolant temperature is greater than 140°F (60°C). Using scan tool, monitor O2S1 voltage. O2S1 voltage should be varying from less than 391 millivolts to greater than 491 millivolts. If voltage is varying as specified, problem is intermittent. See DIAGNOSTIC AIDS  . If voltage is not varying as specified, go to next step.
  2. Turn ignition on, with engine off. Disconnect O2S1 harness connector. Jumper O2S1 harness connector terminal to ground. If scan tool reads less than 100 millivolts, check for loose connections or faulty O2S1. If scan tool does not read less than 100 millivolts, go to next step.
  3. Remove jumper wire. Using a DVOM, check voltage at O2S1 harness connector terminal. If voltage reading is 300-600 millivolts, replace PCM. If voltage reading is greater than 600 millivolts, check for open ground circuit, loose connections or faulty PCM. If voltage reading is less than 300 millivolts, check for open signal circuit, loose connections or faulty PCM.
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