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Home >> Saturn >> 2001 >> SC2 Automatic, MP6 >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P0140: Ho2S2 Circuit - Insufficient Activity >> Diagnostic Procedures

Diagnostic Procedures

NOTE: If DTC P0037 or P0038 are set, diagnose affected DTC(s) first. See DTC P0037: HO2S HEATER CONTROL CIRCUIT LOW  or DTC P0038: HO2S HEATER CONTROL CIRCUIT HIGH  .
  1. Operate engine for 3 minutes. Connect scan tool. Ensure ECT is at greater than 140°F (60°C). Increase engine speed to 3000 RPM. Monitor HO2S2 voltage. HO2S2 voltage should be varying greater than 461 millivolts or less than 426 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 engine off. Disconnect HO2S2 harness connector. HO2S2 harness connector is located on top of rear cradle crossmember. Using a jumper wire, jumper HO2S2 harness connector terminals "A" (Tan wire) and "B" (Purple/White wire). See Figure. Turn ignition on, with engine off. Monitor scan tool. If scan tool reads less than 100 millivolts, check harness connector terminals or possible faulty HO2S2. If scan tool does not read less than 100 millivolts, go to next step.
  3. Remove jumper wire. Connect jumper wire between HO2S2 harness connector terminal "B" (Purple/White wire) and chassis ground. If scan tool reads less than 100 millivolts, check for open in Tan wire, loose connections to PCM or faulty PCM. If scan tool does not read less than 100 millivolts, check for open in Purple/White wire, loose connections to PCM or faulty PCM.
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