Part 1
2AZ-FXE ENGINE CONTROL SYSTEM: SFI SYSTEM: P0441: Evaporative Emission Control System Incorrect Purge Flow
DTC P0441 - Evaporative Emission Control System Incorrect Purge Flow
DTC SUMMARY
DESCRIPTION
While the engine is running, if a predetermined conditions (closed loop, etc.) are met, the purge VSV is opened by the ECM (included in the hybrid vehicle control ECU) 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 to enter into the canister through the vent valve to ensure that purge flow is maintained when negative pressure (vacuum) is applied to the canister.
The ECM monitors the condition of both the key-off monitor and purge flow monitor to ensure proper operation of the 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 (included in the hybrid vehicle control ECU) 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.
1. KEY-OFF MONITOR
(a) Purge VSV stuck open
In operation C, the vacuum pump creates negative pressure (vacuum) in the EVAP (Evaporative Emission) system. The EVAP system pressure is then measured by the ECM (included in the hybrid vehicle control ECU) using the pressure sensor. If the stabilized system pressure is higher than [second 0.02 inch leak pressure standard x 0.2], the ECM (included in the hybrid vehicle control ECU) 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 pressure sensor measures the EVAP (Evaporative Emission) system pressure. The pressure measurement for Purge VSV monitor begins when the Purge VSV is turned ON (open) after the EVAP leak check. When the measured pressure indicates an increase of 0.3 kPa (2.25 mmHg) or more, the Purge VSV is functioning normally. If the pressure does not increase, the ECM (included in the hybrid vehicle control ECU) 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 the two 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 (included in the hybrid vehicle control ECU) 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 (3.75 mmHg), the ECM (included in the hybrid vehicle control ECU) 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 in atmospheric pressure, before and after conducting of the purge flow monitor is measured by the ECM.
MONITOR STRATEGY
TYPICAL ENABLING CONDITIONS
All:
Purge flow:
Purge VSV stuck open and closed:
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
TYPICAL MALFUNCTION THRESHOLDS
Purge VSV stuck open:
Purge VSV stuck open and closed:
Purge flow:
MONITOR RESULT
Refer to the EVAP System .
INSPECTION PROCEDURE
1. CONFIRM DTC
(a) Turn the power switch off and wait 10 seconds.
(b) Turn the power switch on (IG).
(c) Turn the power switch off and wait 10 seconds.
(d) Connect the Techstream to the DLC3.
(e) Turn the power switch on (IG) and turn the tester on.
(f) Enter the following menus: Powertrain / Engine / Trouble Code.
(g) Confirm the DTCs.
DTC and Malfunction Cross-Reference:
NEXT -- Continue to next step.
2. PERFORM SYSTEM CHECK (EVAPORATIVE SYSTEM CHECK (AUTOMATIC OPERATION))
NOTICE:
- In Evaporative System Check (Automatic Mode), a series of 6 Evaporative System Check steps are performed automatically. A maximum of 15 minutes is required.
- Do not perform Evaporative System Check when the fuel tank is more than 90% full because the cut-off valve may be closed and the leak check of the fuel tank is unavailable.
- Do not run the engine.
- When the temperature of the fuel is 35°C (95°F) or more, a large amount of vapor forms and any check results become inaccurate. When performing an Evaporative System Check, keep the temperature below 35°C (95°F).
(a) Clear the DTCs with the Techstream.
(b) Remove the fuel tank cap and reinstall the fuel cap.
(c) Enter the following menus: Powertrain / Engine / Utility / Evaporative System Check / Automatic Mode.
(d) After Evaporative System Check is completed, check for DTCs.
Result:
C -- END
B -- PERFORM SYSTEM CHECK (EVAPORATIVE SYSTEM CHECK (MANUAL OPERATION))
A -- Continue to next step.
3. IDENTIFICATION OF TROUBLE AREAS
(a) Identification of trouble areas according to DTCs.
(b) Refer to the table below to determine the next procedure according to the output DTCs.
Result:
B -- PERFORM ACTIVE TEST USING TECHSTREAM (VACUUM PUMP)
A -- Continue to next step.
4. IDENTIFICATION OF TROUBLE AREAS
(a) Identification of trouble areas according to DTCs.
(b) Refer to the table below to determine the next procedure according to the output DTCs.
Result:
D -- CHECK FUEL VAPOR-CONTAINMENT VALVE ASSEMBLY (POWER SOURCE CIRCUIT)
C -- LOCATE EVAP LEAK PART (FUEL VAPOR-CONTAINMENT VALVE - FUEL TANK)
B -- LOCATE EVAP LEAK PART (PURGE VSV - CANISTER)
A -- Continue to next step.
5. CHECK VACUUM HOSE (PURGE VSV - INTAKE MANIFOLD)
(a) Disconnect the hose (to intake manifold) from the purge VSV.
(b) Put the engine in inspection mode Component Tests and General Diagnostics.
(c) Use your finger and confirm that the purge VSV has suction.
Result:
NG -- REPAIR OR REPLACE VACUUM HOSE
OK -- Continue to next step.
6. PERFORM ACTIVE TEST USING TECHSTREAM (PURGE VSV)
(a) Disconnect the hose (to canister) from the purge VSV.
(b) Put the engine in inspection mode Component Tests and General Diagnostics.
(c) Enter the following menu: Powertrain / Engine / Active Test / Activate the VSV for EVAP Control.
(d) Turn the purge VSV OFF (Purge VSV: OFF).
(e) Use your finger and confirm that the purge VSV has no suction.
(f) Turn the purge VSV ON (Purge VSV: ON).
(g) Use your finger to confirm that the purge VSV has suction.
OK:
Purge VSV functions normally
OK -- REPAIR OR REPLACE VACUUM HOSE
NG -- Continue to next step.
7. CHECK PURGE VSV
(a) Remove the purge VSV.
(b) Apply compressed air to the purge VSV, confirm that no air flows from A to B as shown in the illustration.
(c) Apply battery voltage to the purge VSV.
(d) While applying compressed air, confirm that air flows from A to B as shown in the illustration.
Result:
NG -- REPLACE PURGE VSV
OK -- Continue to next step.
8. CHECK HARNESS AND CONNECTOR (PURGE VSV - EFI NO. 3 FUSE)
(a) Disconnect the C6 purge VSV connector.
(b) Turn the power switch on (IG).
(c) Measure the voltage between terminal 1 of the C6 connector and body ground.
Result:
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.
9. CHECK HARNESS AND CONNECTOR (PURGE VSV - HYBRID VEHICLE CONTROL ECU)
(a) Disconnect the C64 hybrid vehicle control ECU connector and the C6 purge VSV connector.
(b) Measure the resistance.
Standard resistance:
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.
10. REPLACE HYBRID VEHICLE CONTROL ECU
(a) Replace the hybrid vehicle control ECU Removal.
NEXT -- PERFORM SYSTEM CHECK (EVAPORATIVE SYSTEM CHECK AGAIN (AUTOMATIC OPERATION))