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Home >> Saturn >> 1996 >> SC2 Automatic, MP6 >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes >> Diagnostic Trouble Codes >> DTC P0140 - Ho2S Circuit Open/Inactive Sensor 2 >> Diagnostic Procedures
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Diagnostic Procedures

  1. If DTC P0140 and P0141 are both set, diagnose DTC(s) first using DTC P0141 test. Operate engine for 3 minutes or greater. Connect scan tool. Ensure ECT is at greater than 140°F (60°C). Monitor HO2S voltage. HO2S voltage should be varying at less than 350 mV to greater than 500 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 engine off. Turn ignition on, with engine off. Disconnect HO2S harness connector. Using a jumper wire, jumper HO2S harness connector terminals "A" and "B". If scan tool reads less than 100 mV, check tightness of harness connector terminals. If scan tool reads greater than 100 mV, go to next step.
  3. Remove jumper wire. Connect jumper wire between HO2S harness connector terminal "B" and chassis ground. If scan tool reads less than 100 mV, check for open in ground circuit between sensor and chassis ground. If scan tool reads greater than 100 mV, go to next step.
  4. Remove jumper wire. Check voltage reading to HO2S signal circuit at harness connector terminal "B". If voltage is 300-600 mV, replace PCM. If voltage is greater than 600 mV, check for open ground circuit, terminal tightness or faulty PCM. If voltage is less than 300 mV, check for open signal circuit, terminal tightness or faulty PCM.
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