P0441

DTC P0441 EVAPORATIVE EMISSION CONTROL SYSTEM INCORRECT PURGE FLOW




Contents




DTC Summary

Circuit Description







While the engine is running, if a predetermined condition (closed loop, etc.) is met, the purge VSV is opened by the ECM and stored fuel vapors in the canister are purged to the intake manifold. The ECM will change the duty cycle ratio of the purge VSV to control purge flow volume.
Purge flow volume is also determined by the intake manifold pressure. Atmospheric pressure is allowed into the canister through the vent valve to ensure that purge flow is maintained when negative pressure (vacuum) is applied to the canister.

Two monitors are run to confirm proper EVAP system operation.

Key-off monitor
This monitor checks for EVAP system leaks and pump module malfunctions. The monitor starts 5 hours ((+) 15 minutes) after the ignition switch is turned OFF. The 5 hours are required to allow enough time for the fuel to cool down. As a result, Fuel Tank Pressure (FTP) becomes stable and EVAP system monitor will be more accurate. Then, the electric vacuum pump creates negative pressure (vacuum) in the EVAP system and the pressure is measured. Finally, the ECM monitors for EVAP system leaks and pump module malfunctions based on EVAP pressure.

Purge flow monitor
















If EVAP system pressure change is less than 7.5 mmHg (1 kPa) when the engine is running and the purge VSV is turned ON (closed), the ECM determines that the purge flow is insufficient.

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Inspection Procedure

NOTE: When a vehicle is brought into the workshop, leave it as is. Do not change the vehicle condition. For example, do not tighten the fuel cap. Do not disassemble the pump module.

HINT: Using the hand held tester's monitor result allows you to confirm the EVAP system condition.

Monitor Description

Two monitors are run to confirm proper EVAP system operation. The "Key-off" monitor runs when the ignition switch is turned OFF and 5 hours have passed. The "purge flow" monitor runs when the engine is running.

1. KEY-OFF MONITOR







When 5 hours have elapsed after the ignition switch is turned OFF, the electric vacuum pump creates negative pressure (vacuum) in EVAP system. Then ECM monitors for leaks and actuator malfunctions based on EVAP pressure.




a. Purge VSV stuck open
For order D, the vacuum pump creates negative pressure (vacuum) in the EVAP system. Then the pressure is measured. If the stabilized pressure is higher than "(0.02 inch leak pressure) x 0.2", the ECM determines that the purge VSV is stuck open.




b. Purge VSV stuck closed
For order F, after the vacuum pump turns OFF, the pressure sensor measures the EVAP system pressure when the purge VSV has been turned ON (open). If the pressure increases 2.25 mmHg (0.3 kPa) at this time, the ECM determines that the purge VSV is operating normally. If the pressure does not increase, the ECM determines that the purge VSV is stuck closed.

2. PURGE FLOW MONITOR




The purge flow monitor runs a monitor (a), and then runs another monitor (b) if necessary.
a. 1st monitor
When the engine is running and the purge VSV is turned ON (open), the ECM monitors the purge flow by measuring the EVAP pressure change. If negative pressure is not created, the ECM starts the next monitor.
b. 2nd monitor
The vent valve is turned ON (closed) and the EVAP system pressure is measured. If pressure change is less than 7.5 mmHg (1 kPa), the purge VSV may be stuck closed. The ECM illuminates the MIL and sets DTC 0441 (2-trip detection logic).

OBDII Monitor Specification (Key-off Monitor):

OBDII Monitor Specification (Key-off Monitor)

OBDII Monitor Specification (Purge Flow Monitor):

OBDII Monitor Specification (Purge Flow Monitor)