P0441

DTC P0441 Evaporative Emissions Control System Incorrect Purge Flow:

Evaporative Emissions Control (EVAP) System:

CIRCUIT DESCRIPTION
Canister purge is controlled by a solenoid valve that allows ported vacuum to purge the canister when energized. The Vehicle Control Module-A (VCM-A) supplies a ground to energize the solenoid valve (purge "ON"). The purge solenoid control by the VCM-A is Pulse Width Modulated (PWM) or turned "ON" and "OFF" several times a second. The duty cycle (pulse width) is determined by "Closed Loop" feed back from the Heated Oxygen Sensor (HO2S). The duty cycle is calculated by the VCM-A and the output is commanded when certain conditions have been met.

A vacuum switch in the purge line is used to detect when the system is being purged. The normally closed switch will open when less than .3 kPa (1 Hg) is present in the purge line. The VCM-A supplies a 5 volt reference to the switch to monitor if the evaporative emission control system is working properly. If the switch is closed (no purge detected) when the VCM-A is commanding purge, a DTC will be set. DTC P0441 is a type "B" DTC.

DTC PO441 WILL SET WHEN
^ Purge solenoid diagnostic vacuum switch DTC not set.
^ No Idle Air Control (IAC) DTCs set.
^ No Manifold Absolute Pressure (MAP) DTCs set.
^ No Throttle Position (TP) sensor DTCs.
^ No Exhaust Gas Recirculation (EGR) DTCs set.
^ Barometric Absolute Pressure (BARO) is greater than 75 kPa (166 Hg).
^ Engine Coolant Temperature (ECT) is no more than 110°C (230°F).
^ Powerup Intake Air Temperature (IAT) is greater than -18°C (-2°F).
^ IAT is no more than 90°C (194°F).
^ Change in ECT/IAT is no more than 90°C (194°F).
^ Purge Direct Current (DC) is greater than 90%.
^ MAP is greater than 20 kPa (6 Hg).
^ Throttle position is between 5% and 60%.
^ Engine speed is between 800 RPM and 3000 RPM.
^ Evaporative Emissions (EVAP) System purge vacuum switch closed for greater than 4 seconds.

ACTION TAKEN (VCM-A WILL DEFAULT TO)
The VCM-A will turn "ON" Malfunction Indicator Lamp (MIL) after consecutive test cycles with the fault active.

DTC PO441 WILL CLEAR WHEN
The VCM-A will turn the MIL "OFF" after three consecutive trips without a fault condition present. A history DTC will be cleared if no fault conditions have been detected for forty warm-up cycles [coolant temperature has risen 22°C (40°F) from start-up coolant temperature and engine coolant temperature exceeds 71°C (160°F) that same ignition cycle] or the Tech 1 clearing feature has been used.

DTC CHART TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.
1. The solenoid valve will "click" when commanded "ON" and "OFF" by the Tech 1. This determines if the VCM-A can control the solenoid valve.
2. Ported (off idle) vacuum is used at the solenoid valve. Vacuum will only be seen off idle with a vacuum gauge.
3. If voltage is not available to the solenoid valve, the VCM-A will not be able to commanded it "ON" or "OFF."
4. Disconnecting the vacuum switch electrical connector opens the 5 volt reference circuit from the VCM-A which indicates that purge is present. Leaving the switch disconnected will cause a DTC P1441.
5. Determines if the solenoid valve couldn't be commanded due to an electrical circuit problem or faulty solenoid.

DIAGNOSTIC AIDS
Make a visual check of vacuum hose(s). Check throttle body for possible cracked, broken, or plugged vacuum block. Check engine for possible mechanical problem.