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Home >> GMC >> 2011 >> Yukon Base, 5.3 3 >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 14 (Engine Controls And Fuel - Hybrid (LZ1) - DTC P0351 Through DTC P3449 And Troubleshooting) >> Diagnostic Information and Procedures >> DTC P1400 >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different variant/trim than selected.
  1. Inspect the air intake system for the following:
    • Damage, restriction, or modification
    • Dirty or deteriorating air filter element
    • Crankcase ventilation system for correct operation-Refer to Crankcase Ventilation System Inspection/Diagnosis .
    • Water intrusion
    • Vacuum leak and other un-metered air downstream of the mass air flow (MAF) sensor
    • Intake manifold leak
  2. Inspect the exhaust system for the following:
  3. Inspect the engine mechanical for items that could alter the air flow into the combustion chamber. Refer to Symptoms - Engine Mechanical .