[blazee]

P0444 isn't a code caused by the gas cap.

Approximately 20%of all hydrocarbon (HC)emissions from the automobile originate from evaporative sources.The Evaporative Emission Control (EVAP)system is designed to store and dispose of fuel vapors normally created in the fuel system;thereby,preventing its escape to the atmosphere.The EVAP system delivers these vapors to the intake manifold to be burned with the normal air/fuel mixture.This fuel charge is added during periods of closed loop operation when the additional enrichment can be managed by the closed loop fuel control system. Improper operation of the EVAP system may cause rich driveability problems,as well as failure of the Two Speed Idle test or Enhanced I/M evaporative pressure or purge test.

The EVAP system is a fully closed system designed to maintain stable fuel tank pressures without allowing fuel vapors to escape to the atmosphere.Fuel vapor is normally created in the fuel tank as a result of evaporation.It is then transferred to the EVAP system charcoal canister when tank vapor pressures become excessive.When operating conditions can tolerate additional enrichment,these stored fuel vapors are purged into the intake manifold and added to the incoming air/fuel mixture.

The circuit you are talking about is the one that the PCM uses to operate the purge valve. During the system test, the PCM opens the valve. When the valve is open the engine applies vacuum to the tank. The PCM then monitors the rate at which the vacuum disipates through a pressure sensor that is in the tank. By doing this it can detect a leak as small as .020". If it senses a leak it will set a DTC. The most common cause is a loose gas cap.

During normal operation, the PCM opens the purge valve to relieve the pressure in the tank.

The code you had was because the PCM sensed a problem with the circuit not a leak.