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Home >> Cadillac >> 2021 >> CT4 Sport, 4WD >> Repair and Diagnosis >> External Pages >> Different car >> Section 402 (Engine Controls And Fuel - 6.2L (LT4) - Diagnostic Information And Procedures (2 Of 3)) >> Diagnostic Information And Procedures >> DTC P0191, P0192, P127C, P128A, P128B, U0625, or U101B >> Circuit/System Verification

Circuit/System Verification

WARNING: This page is about a different car, the 2022 Cadillac CT5. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition - On/Vehicle - In Service Mode
  2. Verify DTC P0601 - P0607, P0641, P0651, P0697, P06A3 is not set.
    • Go to next step: If none of the DTCs are set 
  3. Verify DTC P0191, P0192, P127C, P128A, P128B, U0625, U101B is not set and no other DTCs are set.
    • If DTC U0625, U101B is not set and other DTCs are set 

      Replace the component: B310 Fuel Pressure/Temperature Sensor

    • If DTC U0625, U101B is set and no other DTCs are set 

      Refer to: Circuit/System Testing

    • Go to next step: If none of the DTCs are set 
  4. Verify the scan tool parameter: Fuel Rail Pressure Sensor = The value should not spike or drop out.

    Perform the action while monitoring the parameter:

    • Wiggle the harness and connector: B310 Fuel Pressure/Temperature Sensor
    • Wiggle the harness and connector: K20 Engine Control Module
    • If the value spikes or drops out 

      Repair as necessary - Wiring/Terminal(s)/Electrical Connector(s)

    • Go to next step: If the value does not spike or drop out 
  5. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

    Verify the DTC does not set.

    • If the DTC sets 

      Refer to: Circuit/System Testing

    • Go to next step: If the DTC is not set 
  6. All OK.
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