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Home >> Cadillac >> 1999 >> Seville STS >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - Tests W/Codes - DTC P0100-P0134 >> DTC P0134 >> DTC P0134: O2S Circuit-Insufficient Activity-Sensor 1 (1.9L SATURN) >> Diagnostic Procedures
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Diagnostic Procedures

  1. Start and operate engine for more than 5 minutes. Connect scan tool. Ensure engine coolant temperature is greater than 140°F (60°C). O2S voltage should be varying from less than 391 mV to greater than 491 mV. 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 O2S harness connector. Jumper O2S harness connector terminal to ground. If scan tool reads less than 100 mV, check for terminal tightness or faulty O2S. If scan tool does not read less than 100 mV, go to next step.
  3. Remove jumper wire. Using a DVOM, measure voltage at O2S harness connector terminal. If voltage reading is.3-.6 volt (300-600 millivolt), replace PCM. If voltage reading is greater than.6 volt (600 millivolt), check for open ground circuit, terminal tightness or faulty PCM. If voltage reading is less than.3 volt (300 millivolt), check for open signal circuit, terminal tightness or faulty PCM.
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