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Home >> Isuzu >> 2007 >> i-290 LS, Standard >> Repair and Diagnosis >> External Pages >> Different car >> Section 65 (Engine Control System & Fuel System - 4.6L - DTC P0351 To P2440) >> DTC P0401 >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2007 Cadillac DTS. However, it is still accessible from the selected car via links, so may be relevant.
  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
      • 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. Refer to Exhaust Gas Recirculation Valve Replacement .
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