The evaporative emission control system prevents hydrocarbon (HC) vapors from the fuel tank from escaping into the atmosphere where they could form photochemical smog. Gasoline vapors are collected in the charcoal canister. The PCM controls the Purge Control Solenoid Valve (PCSV) to purge any collected vapors from the canister back to the engine for combustion. This valve is actuated by the purge control signal from the PCM and controls fuel vapor from the canister to the intake manifold.
If there is Open in PCSV circuit, PCM sets DTC P0444.
Item
Detecting Condition
Possible cause
DTC Strategy
Circuit check, open
Poor connection
Open or short to ground in harness
PCSV
PCM
Enable Conditions
-
Threshold value
Open
Diagnosis Time
Continuous
MIL On Condition
2 driving cycles
Coil resistance(?)
22.0 ~ 26.0 O (20?)
Fig.1) Normal waveform of PCSV under control condition.
The Purge Control Solenoid Valve(PCSV) is open or closed by PCM and vacuum of intake manifold. At opening, fuel vapor from canister enters into intake manifold. To prevent vacuum from forming inside canister, PCM controls to open it. This photo shows the signal waveform of PCSV operating normally.