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Home >> Hummer >> 2008 >> H2 4D Utility Wagon >> Repair and Diagnosis >> External Pages >> Different car >> Section 364 (Engine Controls And Fuel - 5.3L, 6.0L & 6.2L - DTC P0443 Through DTC P3449 And Troubleshooting) >> Diagnostic Information and Procedures >> DTC P0446 >> Circuit/System Testing >> Restriction

Circuit/System Testing: Restriction

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  1. Engine running, the EVAP canister vent solenoid valve open, and the EVAP canister purge solenoid valve commanded to 100 percent, the fuel tank vacuum should not increase to greater than -15 mmHg (-8 inches H2O).
    • If greater than the specified value, isolate the restriction by disconnecting one component at a time while the EVAP canister purge solenoid valve is commanded to 100 percent and the vent valve is open.
  2. Decrease the canister purge duty cycle from 100 percent to 0 percent with a scan tool. The vacuum should decrease to near zero.
    • If not the specified value or appears to decrease too slowly, inspect the components in the EVAP vent system for a restriction.
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