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Home >> Chevrolet >> 2017 >> Malibu LS >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 29 (Engine Controls And Fuel - 1.8L (LKN) - DTC P0446 To DTC P2635 And Diagnostic Information And Procedures) >> Diagnostic Information and Procedures >> DTC P2450: Evaporative Emission (EVAP) System Leak Detection Pump Switching Valve Performance >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different variant/trim than selected.
NOTE: Ensure that the vehicle underbody temperature is similar to the ambient temperature and allow the surrounding air to stabilize before starting the diagnostic procedure.
  1. Vehicle in Service Mode.
  2. Verify the following scan tool parameters when commanding the EVAP Test ON.
    • The EVAP Leak Detection Pump Command should show ON.
    • The EVAP Leak Detection Pump Switching Valve Command should change from Venting to Not Venting.
    • If not within specified range 

      Replace the Q63 Evaporative Emission System Leak Detection Pump Assembly

    • If within specified range 
  3. Verify and record the EVAP leak detection pump pressure and fuel tank pressure. Both pressures should drop
    • If status changes, but no pressure drop 
  4. Remove the vent pipe and the fresh air pipe from the EVAP leak detection pump assembly
  5. Verify the pump openings for any of the conditions listed below
    • The EVAP leak detection pump to the vent solenoid tube and clamps for damage or restriction
    • Missing or damaged EVAP leak detection pump O-rings
    • The fresh air tube near the fuel fill pocket for a restriction
    • The fresh air tube for a restriction

      Repair or replace any of the above components.

    • If all components test normal 

      Replace the Q63 Evaporative Emission System Leak Detection Pump Assembly.

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