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Home >> Saturn >> 2000 >> SC2 Standard, MP2 >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P0140: Ho2S Circuit - Insufficient Activity - Sensor 2 >> Diagnostic Procedures

Diagnostic Procedures

NOTE: If DTC P0037 or P0038 is 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 mV or less than 426 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. Disconnect HO2S2 harness connector. Using a jumper wire, jumper HO2S2 harness connector terminals "A" (Tan wire) and "B" (Purple/White wire) together. Turn ignition on, with engine off. Monitor scan tool. If scan tool reads less than 100 mV, check tightness of harness connector terminals. If scan tool does not read less than 100 mV, 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 mV, check for open in Tan wire or for terminal tightness to PCM. If scan tool does not read less than 100 mV, check for open in Purple/White wire or for terminal tightness to PCM.
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