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Home >> Hyundai >> 2017 >> Sonata Plug-In Hybrid >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System Diagnosis (PHEV) (3 Of 3) >> DTC P2251: O2 Sensor Reference Ground Circuit/Open (Bank 1 / Sensor 1) >> Component Inspection
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Component Inspection

■ HO2S Visual Inspection 

  1. IG "OFF" & Disconnect HO2S (S1) connector.
  2. Check that HO2S (S1) is contaminated or damaged by foreign materials.
  3. Has a problem been found?

    YES 

    • Substitute with a known-good HO2S and check for proper operation. If the problem is corrected, replace HO2S and then go to "Verification of Vehicle Repair " procedure.

    NO 

    • Go to next step.

■ HO2S Performance Inspection 

  1. IG KEY "OFF".
  2. Connect probe to signal terminal of HO2S (S1) connector and select oscilloscope function with GDS.
  3. Warm up the engine to normal operating temperature.
  4. Measure signal waveform of HO2S (S1) with GDS.

    Specification:  Refer to Signal Waveform & Data 

  5. Is the measured signal waveform within specification?

    YES 

    • Check for poor connection between PCM and component: backed out terminal, improper mating, broken locks or poor terminal to wire connection. Repair as necessary and go to "Verification of Vehicle Repair " procedure.

    NO 

    • Substitute with a known-good HO2S and check for proper operation. If the problem is corrected, replace HO2S and then go to "Verification of Vehicle Repair " procedure.
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