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Home >> Kia >> 2012 >> Optima Hybrid >> Repair and Diagnosis (Single Page) >> Engine Performance >> System >> Engine Control System Diagnosis (2 Of 2) - HEV >> DTC P2251: O2 Sensor Reference Ground Circuit Open-Bank 1 Sensor 1 >> General Information >> DTC Detecting Condition
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General Information: DTC Detecting Condition

Item Detecting Condition Possible Cause
DTC Strategy
  • Reference ground circuit open (VG)
  1. Poor connection or damaged harness
  2. Open in HO2S control circuit
  3. Front HO2S
Enable Conditions
  • 11V < Battery voltage < 16V
Threshold Value
  • 1.9V < Signal < 2.1V for 5sec during internal test
  • Symptom detected on no activity
  • Signal < 2.1V during fuel cut off
Diagnostic Time
  • Within 15sec. after related symptom detected.
MIL On Condition
  • 2 Driving Cycles
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