P0441

2UR-FSE ENGINE CONTROL SYSTEM: SFI SYSTEM: P0441: Evaporative Emission Control System Incorrect Purge Flow
P0441 - Evaporative Emission Control System Incorrect Purge Flow

DTC SUMMARY





DESCRIPTION

Refer to the EVAP System EVAP System.

MONITOR DESCRIPTION

The two monitors, Key-Off and Purge Flow, are used to detect malfunctions relating to DTC P0441. The Key-Off monitor is initiated by the ECM internal timer, known as the soak timer, 5 hours* after the power switch is turned off. The purge flow monitor runs while the engine is running.

HINT
*: If the engine coolant temperature is not below 35°C (95°F) 5 hours after the power switch is turned off, the monitor check starts 2 hours later. If it is still not below 35°C (95°F) 7 hours after the power switch is turned off, the monitor check starts 2.5 hours later.

1. KEY-OFF MONITOR

a. Purge VSV stuck open

In operation C, the leak detection pump creates negative pressure (vacuum) in the EVAP system. The EVAP system pressure is then measured by the ECM using the canister pressure sensor. If the stabilized system pressure is higher than [second reference pressure x 0.2], the ECM interprets this as the purge VSV (Vacuum Switching Valve) being stuck open. The ECM illuminates the MIL and sets the DTC (2 trip detection logic).

b. Purge VSV stuck closed

In operation D, the canister pressure sensor measures the EVAP system pressure. The pressure measurement for purge VSV monitor is begun when the purge VSV is turned ON (open) after the EVAP leak check. When the measured pressure indicates an increase of 0.3 kPa-g (2.25 mmHg-g) or more, the purge VSV is functioning normally. If the pressure does not increase, the ECM interprets this as the purge VSV being stuck closed. The ECM illuminates the MIL and sets the DTC (2 trip detection logic).





2. PURGE FLOW MONITOR

The purge flow monitor consists of 2 step monitors. The 1st monitor is conducted every time and the 2nd monitor is activated if necessary.





- The 1st monitor

While the engine is running and the purge VSV (Vacuum Switching Valve) is ON (open), the ECM monitors the purge flow by measuring the EVAP pressure change. If negative pressure is not created, the ECM begins the 2nd monitor.

- The 2nd monitor

The vent valve is turned ON (closed) and the EVAP pressure is then measured. If the variation in the pressure is less than 0.5 kPa-g (3.75 mmHg-g), the ECM interprets this as the Purge VSV being stuck closed. The ECM illuminates the MIL and sets DTC P0441 (2 trip detection logic).

Atmospheric pressure check:

In order to ensure reliable malfunction detection, the variation between the atmospheric pressure, before and after conduction of the purge flow monitor is measured by the ECM.

MONITOR STRATEGY





TYPICAL ENABLING CONDITIONS

Key-off monitor:





Key-off monitor sequence 1 to 15

1. Atmospheric pressure measurement





2. First reference pressure measurement





3. Vent valve stuck closed check





4. Vacuum introduction for canister





5. Purge VSV stuck closed check





6. Second reference pressure measurement





7. Canister leak





8. Fuel vapor-containment valve (FVCV stuck closed check)





9. Vacuum introduction for fuel tank





10. FVCV stuck closed check





11. FTP sensor stuck check





12 Third reference pressure measurement





13. Fuel tank leak check





14. FTP sensor stuck check





15. Atmospheric pressure measurement





HINT
"Saturated" indicates that the EVAP pressure change in less than 0.12 kPa (0.9 mmHg) in 30 seconds.

Purge flow monitor:





TYPICAL MALFUNCTION THRESHOLDS

Purge VSV stuck open:





Purge VSV stuck closed:





Purge flow:





MONITOR RESULT

Refer to CHECKING MONITOR STATUS Mode 6 Data.

WIRING DIAGRAM

Refer to the EVAP System EVAP System.

INSPECTION PROCEDURE

Refer to the EVAP System EVAP System.