2004 Boxster - I checked the purge valve under the manifold and the connector is solid, with no broken wires. I replaced the purge valve anyway even though it was functioning when 12V was applied to the valve. The code comes back after being cleared within a few minutes. I also checked the purge valve under the fender liner by the gas cap, and it works when voltage is applied. I also tried replacing the gas cap and fuel tank vent valve with no luck! Any ideas?