Locate the purge valve
Disconnect the electrical connector
Remove the vacuum hose
Check for visible damage or cracks
Apply vacuum to the valve
Verify the valve holds vacuum when de-energized
Apply battery voltage to the valve terminals
Listen or feel for the valve clicking
Recheck airflow through the valve when energized
Use a multimeter to test coil resistance
Compare resistance to manufacturer specifications
Scan for diagnostic trouble codes
Test the valve with a scan tool if available
Replace the valve if it fails any test