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Home >> GMC >> 2006 >> Sierra 1500 HD, RWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 1655 (Engine Control System & Fuel System - Hybrid (Hp2) 6.0L (LZ1) - DTC P1380 To DTC P3449) >> DTC P1400 >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2010 GMC Sierra and 2010 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.
  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 .