Large Leak Test

2001 Chevrolet Astro Van L AWD V6-4.3L VIN WSECTION Large Leak Test
This tests for large leaks and blockages in the EVAP system. The control module will command the EVAP vent valve ON (closed) and command the EVAP purge valve ON (open) with the engine running, allowing engine vacuum into the EVAP system. The control module monitors the Fuel Tank Pressure (FTP) sensor to verify that the system is able to reach a predetermined level of vacuum within a set amount of time. The control module then commands the EVAP purge valve OFF (closed), sealing the system and monitors the vacuum level for decay. If the control module does not detect that the predetermined vacuum level was achieved, or the vacuum decay is more than a calibrated level on 2 consecutive tests, a DTC P0440 will set.
RENDER: 1.0x

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • You smell fuel, burning insulation, or see smoke.
  • Brakes feel soft, pull hard to one side, or make grinding noises.
  • The engine overheats, stalls repeatedly, or misfires under load.
  • You are missing required tools, torque specs, or safe lifting equipment.
  • You are not confident in the next step or safety outcome.