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Home >> Cadillac >> 2021 >> CT4 Sport, 4WD >> Repair and Diagnosis >> External Pages >> Different car >> Section 122 (Engine Controls And Fuel - 2.7L (L3B) - Diagnostic Information And Procedures (3 Of 3)) >> Diagnostic Information and Procedures >> DTC P1400 >> Circuit/System Verification

Circuit/System Verification

WARNING: This page is about a different car, the 2022 Cadillac CT4. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition - On / Vehicle - In Service Mode
  2. Verify there are no DTCs set related to the following component/system:
    • B65 Manifold Absolute Pressure and Intake Air Temperature Sensor
    • B75 Mass Airflow Sensor
    • Q17 Fuel Injector
    • Fuel Trim System
    • Go to next step: If a related DTC is not set 
  3. Verify the following conditions do not exist:
    • Air Cleaner Element - Dirty/Water intrusion/Visible Damage
    • Exhaust System
    • Intake Air Duct - Loose/Poor Connection/Restrictions/Visible Damage
    • Intake Manifold - Vacuum leak
    • Mechanical Condition @ Engine - Altered air flow

      For example:

      • Exhaust Port or Intake Port @ Cylinder Head - Casting Flash/Restrictions
      • Exhaust Valve or Intake Valve - Leaking/Stuck
      • Intake Manifold - Casting Flash/Restrictions/Vacuum leak
    • Positive Crankcase Ventilation System - Dirty/Leaking/Poor Connection/Restricted - Refer to: Crankcase Ventilation System Inspection/Diagnosis
    • Vacuum Hoses - Incorrect connection/Kinked/Leaking/Restricted
    • If a condition exists 

      Repair or replace as necessary

    • Go to next step: If no condition exists 
  4. 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 

      A condition with the system still exists - Refer to: Step 3

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