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Home >> Pontiac >> 2009 >> Torrent Base, AWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls And Fuel - 3.4L - DTC P0401 To DTC P2544 >> DTC P0401 >> Circuit/System Testing
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Circuit/System Testing

  1. Verify the following conditions are not present:
    • Incorrect EGR valve for engine application
    • A vacuum leak between the EGR valve and the intake manifold
    • Signs of external leakage usually indicated by carbon buildup around the mating surfaces of the components or an audible exhaust noise
    • Restrictions in the passages or EGR valve caused by carbon deposits or casting flash
    • MAP sensor for being shifted, stuck, skewed, and for correct vacuum supply-Refer to DTC P0106 .
    • IMPORTANT: Restrictions can cause excessive back pressure and low engine vacuum.
    • Leaking, restricted, or modified exhaust system
    • Mechanical failure in the engine such as worn piston rings, camshaft, or incorrect timing components installation-Refer to Symptoms - Engine Mechanical .
  2. If all conditions test normal, replace the EGR valve.