DTC P0446: Evaporative Emission Control System Vent Control Circuit

CIRCUIT OPERATION
• The evaporative emission ventilation solenoid power is supplied from the MFI relay (terminal No. 1).
• The PCM controls the evaporative emission ventilation solenoid ground by turning the power transistor in the PCM ON and OFF.
TECHNICAL DESCRIPTION
• To judge if there is open circuit in the evaporative emission ventilation solenoid drive circuit, PCM measures the surge voltage of the evaporative emission ventilation solenoid coil.
DESCRIPTIONS OF MONITOR METHODS
Off-surge does not occur after solenoid is operated on to off.
MONITOR EXECUTION
Once per driving cycle
MONITOR EXECUTION CONDITIONS (Other monitor and Sensor)

Other Monitor (There is no temporary DTC stored in memory for the item monitored below)
• Not applicable

Sensor (The sensor below is determined to be normal)
• Not applicable
DTC SET CONDITIONS Logic Flow Chart


Check Conditions
Battery positive voltage is at between 10 and 16.5 volts.

Judgment Criteria
• The evaporative emission ventilation solenoid coil surge voltage (battery positive voltage + 2 volts) is not detected for 0.2 second.
• The PCM monitors for this condition once during the drive cycle.

Check Conditions
Battery positive voltage is at between 10 and 16.5 volts.
ON duty cycle of the evaporative emission purge solenoid is 0 percent.
ON duty cycle the EGR vacuum regulator solenoid valve is 0 percent.
Evaporative emission ventilation solenoid is ON.
More than 1 second has elapsed after the above mentioned conditions have been met.

Judgment Criteria
The evaporative emission ventilation solenoid coil surge voltage (battery positive voltage + 2 volts) is not detected for 1 second. When the evaporative emission ventilation solenoid is turned OFF.
OBD-II DRIVE CYCLE PATTERN
Refer to Diagnostic Function - OBD-II Drive Cycle - Procedure 6 - Other Monitor .
TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:
• Evaporative emission ventilation solenoid failed.
• Open or shorted evaporative emission ventilation solenoid circuit, harness damage or connector damage.
• PCM failed.