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Home >> Buick >> 2017 >> Verano Base, Gas >> Repair and Diagnosis (Single Page) >> Engine Performance >> System >> Engine Controls And Fuel - 2.4L (Lea) - DTC P0335 To DTC P2635 And Diagnostic Information And Procedures >> Diagnostic Information and Procedures >> DTC P1400: Cold Start Emission Reduction Control System >> Circuit/System Verification

Circuit/System Verification

  1. Vehicle OFF, allow the engine to cool to be within the temperatures listed in the Conditions for Running the DTC.
  2. Engine running.
  3. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not set. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.
  4. Verify the DTC does not set.
    • If the DTC sets 

      Verify that none of the conditions listed below exists with the air intake system:

    • Damage, restriction, or modification
    • Dirty or deteriorating air filter element
    • Incorrect operation of the crankcase ventilation system
    • Water intrusion
    • Vacuum leaks and other unmetered air downstream of the mass air flow (MAF) sensor
    • Intake manifold leak
    • If any of the above conditions exist 

      Repair as necessary.

    • If none of the conditions exist 
  5. Verify that none of the conditions listed below exists with the exhaust system:
    • If any of the conditions exist 

      Repair as necessary.

    • If none of the conditions exist 

      If all of the above conditions test normal, inspect for an engine mechanical condition that could alter the air flow into the combustion chamber. Refer to Symptoms - Engine Mechanical .

    • If the DTC does not set 
  6. All OK.