Last Modified: 7-3-2017 6.8:8.0.40 Doc ID: RM000000SWF01XX
Model Year Start: 2007 Model: LX470 Prod Date Range: [08/2006 -           ]
Title: 2UZ-FE ENGINE CONTROL SYSTEM: SFI SYSTEM: P0441; Evaporative Emission Control System Incorrect Purge Flow; 2007 MY LX470 [08/2006 -        ]

DTC

P0441

Evaporative Emission Control System Incorrect Purge Flow

DTC SUMMARY

DTC No.

Monitoring Item

Malfunction Detection Condition

Trouble Area

Detection Timing

Detection Logic

P0441

Purge Vacuum Switching Valve (VSV) stuck open

Leak detection pump creates negative pressure (vacuum) in EVAP system and EVAP system pressure measured.

Reference pressure measured at start and at end of leak check.

If stabilized pressure higher than [second reference pressure x 0.2], ECM determines that purge VSV stuck open
  • Purge VSV
  • Connector/wire harness (purge VSV - ECM)
  • ECM
  • Canister pump module
  • Leakage from EVAP system

While ignition switch OFF

2 trip

P0441

Purge VSV stuck closed

After EVAP leak check performed, purge VSV turned ON (open), and atmospheric air introduced into EVAP system.

Reference pressure measured at start and at end of check.

If pressure does not return to near atmospheric pressure, ECM determines that purge VSV stuck closed
  • Purge VSV
  • Connector/wire harness (purge VSV - ECM)
  • ECM
  • Canister pump module
  • Leakage from EVAP system

While ignition switch OFF

2 trip

P0441

Purge flow

While engine running, following conditions successively met:

  • Negative pressure not created in EVAP system when purge VSV turned ON (open)
  • EVAP system pressure change less than 0.5 kPa-g (3.75 mmHg-g) when vent valve turned ON (closed)
  • Atmospheric pressure change before and after purge flow monitor less than 0.1 kPa-g (0.75 mmHg-g)
  • Purge VSV
  • Connector/wire harness (purge VSV - ECM)
  • Leakage from EVAP line (purge VSV - Intake manifold)
  • ECM

While engine running

2 trip

DESCRIPTION

The circuit description can be found in the Evaporative Emission (EVAP) system 2007 MY LX470 [08/2006 -        ]; 2UZ-FE ENGINE CONTROL SYSTEM: SFI SYSTEM: EVAP System+ .

INSPECTION PROCEDURE

Refer to the EVAP system 2007 MY LX470 [08/2006 -        ]; 2UZ-FE ENGINE CONTROL SYSTEM: SFI SYSTEM: EVAP System+ .

MONITOR DESCRIPTION

The 2 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 ignition switch is turned OFF. The purge flow monitor runs while the engine is running.

  1. Key-off monitor

    5 hours* after the ignition switch is turned OFF, the leak detection pump creates negative pressure(vacuum) in the EVAP system. The ECM monitors for leaks and actuator malfunctions based on the EVAP pressure.

    HINT:

    *: If the engine coolant temperature is not below 35°C (95°F) 5 hours after the ignition 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 ignition switch is turned OFF, the monitor check starts 2.5 hours later.

    Sequence

    Operation

    Description

    Duration

    -

    ECM activation

    Activated by soak timer 5, 7 or 9.5 hours after ignition switch OFF.

    -

    A

    Atmospheric pressure measurement

    Vent valve turned OFF (vent) and EVAP system pressure measured by ECM in order to register atmospheric pressure.

    If pressure in EVAP system not between 76 kPa-a and 110 kPa-a (570 mmHg-a and 825 mmHg-a), ECM cancels EVAP system monitor.

    10 seconds

    B

    First reference pressure measurement

    In order to determine reference pressure, leak detection pump creates negative pressure (vacuum) through reference orifice and then ECM checks if leak detection pump and vent valve operate normally.

    60 seconds

    C

    EVAP system pressure measurement

    Vent valve turned ON (closed) to shut EVAP system.

    Negative pressure (vacuum) created in EVAP system, and EVAP system pressure then measured.

    Write down measured value as it will be used in leak check.

    If EVAP pressure does not stabilize within 15 minutes, ECM cancels EVAP system monitor.

    15 minutes*

    D

    Purge VSV monitor

    Purge VSV opened and then EVAP system pressure measured by ECM.

    Large increase indicates normal.

    10 seconds

    E

    Second reference pressure measurement

    After second reference pressure measurement, leak check performed by comparing first and second reference pressure.

    If stabilized system pressure higher than second reference pressure, ECM determines that EVAP system leaking.

    60 seconds

    F

    Final check

    Atmospheric pressure measured and then monitoring result recorded by ECM.

    -

    *: If only a small amount of fuel is in the fuel tank, it takes longer for the EVAP pressure to stabilize.

    1. 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).

    2. 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 the 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 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, and 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

Related DTCs

P0441: Purge VSV stuck open

P0441: Purge VSV stuck closed

P0441: Purge flow

Required Sensors/Components

Purge VSV and canister pump module

Frequency of Operation

Once per driving cycle

Duration

Within 15 minutes (varies with fuel in tank)

MIL Operation

2 driving cycles

Sequence of Operation

None

TYPICAL ENABLING CONDITIONS

Purge Flow Monitor:

Monitor runs whenever following DTC not present

-

Engine

Running

ECT

4.4°C (40°F) or more

IAT

4.4°C (40°F) or more

FTP sensor malfunction

Not detected

Purge VSV

Not detected by scan tool

EVAP system check

Not detected by scan tool

Battery voltage

10 V or higher

Purge duty cycle

8% or more

Purge VSV Stuck:

Enable conditions of EVAP key-OFF monitor

P043E (Reference orifice - low flow)

P043F (Reference orifice - high flow)

P0441 (Purge VSV - stuck open)

P0441 (Purge VSV - stuck close)

P0451 (Canister pressure sensor - noise)

P0455 (EVAP gross leak)

P0456 (EVAP small leak)

P2401 (Leak detection pump - stuck OFF)

P2402 (Leak detection pump - stuck ON)

P2419 (Vent valve - stuck ON)

P2420 (Vent valve - stuck OFF)

Atmospheric pressure

70 to 110 kPa-a (525 to 825 mmHg-a)

Battery voltage

10.5 V or higher

Vehicle speed

Less than 2.5 mph (4 km/h)

Ignition switch

OFF

Time after key off

5 or 7 or 9.5 hours

Canister pressure sensor malfunction (P0450, P0452, P0453)

Not detected

Purge VSV

Not operated by scan tool

Vent valve

Not operated by scan tool

Leak detection pump

Not operated by scan tool

Both of the following conditions 1 and 2 are met before key off

-

1. Duration that vehicle has been driven

5 minutes or more

2. EVAP purge operation

Performed

ECT

4.4 to 35°C (40 to 95°F)

IAT

4.4 to 35°C (40 to 95°F)

1. Key-off monitor sequence 1 to 8

1. Atmospheric pressure measurement

Next sequence is run if the following condition is met

-

Atmospheric pressure change

Less than 0.3 kPa-g (2.25 mmHg-g) in 1 second

2. First reference pressure measurement

Next sequence is run if the following conditions are met

-

EVAP pressure just after reference pressure measurement start

-1 kPa-g (-7.5 mmHg-g) or lower

Reference pressure

-4.85 to -1.05 kPa-g (-36.4 to -7.93 mmHg-g)

Reference pressure

Saturated within 60 seconds

3. Vent valve stuck closed check

Next sequence is run if the following condition is met

-

EVAP pressure change after vent valve is ON

0.3 kPa-g (2.25 mmHg-g) or more

4. Vacuum introduction

Next sequence is run if the following condition is met

-

EVAP pressure

Saturated within 15 minutes

5. Purge VSV stuck closed check

Next sequence is run if the following condition is met

-

EVAP pressure change after purge valve is open

0.3 kPa-g (2.25 mmHg-g) or more

6. Second reference pressure measurement

Next sequence is run if the following conditions are met

-

EVAP pressure just after reference pressure measurement start

-1 kPa-g (-7.5 mmHg-g) or lower

Reference pressure

-4.85 to -1.05 kPa-g (-36.4 to -7.93 mmHg-g)

Reference pressure

Saturated within 60 seconds

Difference between first reference pressure and second reference pressure

Less than 0.7 kPa-g (5.25 mmHg-g)

7. Leak check

Next sequence is run if the following condition is met

-

EVAP pressure when vacuum introduction is complete

Second reference pressure or lower

8. Atmospheric pressure measurement

EVAP monitor is complete if the following condition is met

-

Atmospheric pressure difference between sequence 1 and 8

Within 0.3 kPa-g (2.25 mmHg-g)

TYPICAL MALFUNCTION THRESHOLDS

Purge Flow Monitor:

Both of the following conditions are met

-

EVAP pressure change when purge flow is started

Lower than 0.1 kPa-g (0.75 mmHg-g)

EVAP pressure change during purge flow when EVAP pressure switching valve is ON (closed)

0.5 kPa-g (3.75 mmHg-g) or more

Key-off Monitor: Purge VSV stuck open

FTP when vacuum introduction complete

Higher than reference pressure x 0.2

Key-off Monitor: Purge VSV stuck closed

FTP change after Purge VSV ON (open)

Less than 0.3 kPa-g (2.25 mmHg-g)

MONITOR RESULT

Refer to detailed information on MONITOR RESULT 2007 MY LX470 [08/2006 -        ]; 2UZ-FE ENGINE CONTROL SYSTEM: SFI SYSTEM: EVAP System+ .