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Home >> Cadillac >> 2010 >> Escalade EXT >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System & Fuel System - 5.3L, 6.0L, 6.2L - DTC P1255 To DTC P3449 >> DTC P2271 or P2273 >> Circuit/System Verification
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Circuit/System Verification

  1. Ignition ON, observe the DTC information with a scan tool. Verify that no B52 HO2S heater DTCs are set.
  2. Engine idling, move the appropriate B52 HO2S 2 harness connector and the engine control module (ECM) harness connector while monitoring the B52 HO2S 2 voltage parameter with a scan tool. Verify that the B52 HO2S parameter does not change abruptly while moving the related harnesses.
    • If the B52 HO2S parameter does change abruptly while moving the related harnesses repair the circuit as necessary.
  3. Engine idling at operating temperature, observe the appropriate B52 HO2S 2 parameter with a scan tool. Verify the following:
    • The B52 HO2S 1 value should vary from below 200 mV to above 800 mV and respond to fueling changes.
    • The B52 HO2S 2 should fluctuate at less than 380 mV or greater than 520 mV. The values should not remain within 380 mV and 520 mV.
  4. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.
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