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Home >> GMC >> 2018 >> Terrain Denali, FWD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 7 (Engine Controls And Fuel - 1.5L (LYX) - Diagnostic Information And Procedures (P0351 - P26C8) And Symptoms) >> Diagnostic Information And Procedures >> DTC P1400: Cold Start Emission Reduction Control System >> Circuit/System Verification

Circuit/System Verification

WARNING: This page is about a different variant/trim than selected.
  1. Verify that none of the conditions listed below exists with the air intake system:
    • Damage, restriction, or modification
    • Dirty or deteriorating air filter element
    • Crankcase ventilation system for correct operation
    • Water intrusion
    • Vacuum leak 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.

    • Go to next step: If none of the conditions exist 
  2. Verify that none of the conditions listed below exists with the exhaust system:
    • If any of the above conditions exist 

      Repair as necessary.

    • Go to next step: If none of the conditions exist 
  3. 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 a condition exists - Repair or replace as necessary 
    • Go to next step: If none of the conditions exists 
  4. Vehicle OFF, allow the engine to cool to be within the temperatures listed in the Conditions for Running the DTC.
  5. Engine running.
  6. 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.
  7. Verify the DTC does not set.
    • If the DTC sets 

      Refer to step 1

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