
DI-236
DIAGNOSTICS - ENGINE (1GR-FE)
DIDTP-01
DTC P0441 Evaporative Emission Control System Incor-
rect Purge Flow
DTC SUMMARY
Detection Detection
DTCs Monitoring Items Malfunction Detection Conditions Trouble Areas
Timings Logic
Vacuum pump creates negative pressure
(vacuum) in EVAP system and EVAP sys-
S Purge VSV
tem pressure measured. 0.02 inch leak
S Connector/wire harness
Purge VSV (Vacuum pressure standard is measured at the start
(Purge VSV - ECM) While ignition
P0441 Switching Valve) stuck and at the end of the leak check. 2 trip
S ECM Switch OFF
open If stabilized pressure higher than [second
S Pump module
0.02 inch leak pressure standard x 0.2],
S Leakage from EVAP system
ECM determines that purge VSV stuck
open
After EVAP leak check performed, purge
VSV turned ON (open), and atmospheric S Purge VSV
air introduced into EVAP system. 0.02 inch S Connector/wire harness
leak pressure standard is measured at the (Purge VSV - ECM) While ignition
P0441 Purge VSV stuck closed 2 trip
start and at the end of the leak check. S ECM Switch OFF
If pressure does not return to near atmo- S Pump module
spheric pressure, ECM determines that S Leakage from EVAP system
purge valve stuck closed
While engine running, following conditions
successively met:
S Negative pressure not created in EVAP
S Purge VSV
system when purge VSV turned ON
S Connector/wire harness
(open)
(Purge VSV - ECM) While engine
P0441 Purge flow S EVAP system pressure change less than 2 trip
S Leakage from EVAP line running
0.5 kPa (3.75 mmHg) when vent valve
(Purge VSV - Intake manifold)
turned ON (closed)
S ECM
S Atmospheric pressure change before and
after purge flow monitor less than 0.1 kPa
(0.75 mmHg)
CIRCUIT DESCRIPTION
The circuit description can be found in the EVAP (Evaporative Emission) Inspection Procedure (see page
DI-368).
DI-237
DIAGNOSTICS - ENGINE (1GR-FE)
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 ignition
switch is turned to 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 electric vacuum pump creates negative pressure (vacu-
um) in the EVAP (Evaporative Emission) 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 Operations Descriptions Duration
- ECM activation Activated by soak timer, 5 hours (7 or 9.5 hours) after ignition switch turned to OFF. -
Vent valve turned OFF (vent) and EVAP system pressure measured by ECM in order to
Atmospheric pressure register atmospheric pressure.
A 10 seconds
measurement If EVAP pressure is not between 70 kPa and 110 kPa (525 mmHg and 825 mmHg), ECM
cancels EVAP system monitor.
First 0.02 inch leak In order to determine 0.02 inch leak pressure standard, vacuum pump creates negative pres-
B pressure measure- sure (vacuum) through 0.02 inch orifice and then ECM checks if vacuum pump and vent 60 seconds
ment valve operate normally.
Vent valve turned ON (closed) to shut EVAP system.
Negative pressure (vacuum) created in EVAP system, and EVAP system pressure then
EVAP system pres-
C measured. 15 minutes*
sure measurement
Write down the measured value as it will be used in the leak check.
If EVAP pressure does not stabilize within 15 minutes, ECM cancels EVAP system monitor.
Purge VSV opened and then EVAP system pressure measured by ECM.
D Purge VSV monitor 10 seconds
Large increase indicates normal.
Second 0.02 inch leak Leak check is performed after second 0.02 inch leak pressure standard is measured.
E pressure measure- If stabilized system pressure higher than second 0.02 inch leak pressure standard, ECM 60 seconds
ment determines that EVAP system leaking.
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.
DI-238
DIAGNOSTICS - ENGINE (1GR-FE)
Operation A: Atmospheric Pressure Measurement Operation B: 0.02 Inch Leak Pressure Measurement
Canister
Fuel Tank
Vent Valve: OFF (vent) OFF OFF (vent)
Purge VSV: OFF
0.02 Inch Orifice
Pressure Sensor
Air Filter ON
Vacuum Pump: OFF Pump Module
Operation C: EVAP Leak Check Operation D: Purge VSV monitor
OFF ON (closed) ON ON (closed)
Atmospheric
Pressure
Negative
Pressure
ON ON
A23480
(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 using the pressure sensor. If the stabilized
system pressure is higher than [second 0.02 inch leak pressure standard 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).
EVAP Pressure when Purge VSV Stuck Open:
Purge VSV ON ON: Open
OFF: Closed
Vent Valve ON ON: Closed
OFF: Vent
Vacuum Pump ON
EVAP Pressure Malfunction
Positive
Negative
Second 0.02 inch
Leak Pressure
OK Standard x 0.2
First 0.02 inch
Leak Pressure
Standard
Sequence A B C D E
10 60 10 60
Time sec sec
Within 15 minutes
sec
sec
A23483
DI-239
DIAGNOSTICS - ENGINE (1GR-FE)
(b) Purge VSV stuck closed
In operation D, the 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 (2.25 mmHg) 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).
EVAP Pressure when Purge VSV Stuck Closed:
Purge VSV ON ON: Open
OFF: Closed
Vent Valve ON ON: Closed
OFF: Vent
Vacuum Pump ON
EVAP Pressure
Positive
OK
Negative
Malfunction
First 0.02 inch
Leak Pressure
Standard
Sequence A B C D E
10 60 10 60
Time sec sec
Within 15 minutes
sec
A23484
EVAP Pressure 2. PURGE FLOW MONITOR
During Purge Flow Monitor: The purge flow monitor consists of the two step monitors. The
Purge
1st monitor is conducted every time and the 2nd monitor is acti-
VSV Open vated if necessary.
Vent S The 1st monitor
Valve ON (closed) While the engine is running and the purge VSV
(Vacuum Switching Valve) is ON (open), the ECM
EVAP Malfunction
monitors the purge flow by measuring the EVAP
Pressure
0.1 kPa pressure change. If negative pressure is not
OK created, the ECM begins the 2nd monitor.
0.5 kPa S The 2nd monitor
OK
1st 2nd
The vent valve is turned ON (closed) and the EVAP
Monitor Monitor pressure is then measured. If the variation in the
A23485 pressure is less than 0.5 kPa (3.75 mmHg), 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 pressures, before and after conduc-
tion of the purge flow monitor, is measured by the ECM.
DI-240
DIAGNOSTICS - ENGINE (1GR-FE)
MONITOR STRATEGY
Purge VSV stuck open
Related DTCs P0441 Purge VSV stuck closed
Purge flow
Required sensors/components Purge VSV, Pump module
Frequency of operation Once per driving cycle
Purge VSV stuck open and closed: Within 15 min. (varies with amount of fuel in tank)
Duration
Purge flow: Within 10 min.
MIL operation 2 driving cycle
Sequence of operation None
TYPICAL ENABLING CONDITIONS
Specification
Item
It
Minimum Maximum
The monitor will run whenever these
See page DI-18
DTCs are not present
Purge VSV stuck open and closed:
Atmospheric pressure 70 to 110 kPa (525 to 825 mmHg)
Battery voltage 10.5 V -
Vehicle speed - 2.5 mph (4 km/h)
Ignition switch OFF
EVAP pressure sensor malfunction
Not detected
(P0450, P0452, P0453)
EVAP canister purge valve Not operated by scan tool
EVAP canister vent valve Not operated by scan tool
EVAP leak detection pump Not operated by scan tool
Both of the following conditions are met
Condition 1 and 2
before IG switch OFF
1. Duration that vehicle is driven 5 min. -
2. EVAP purge operation Performed
ECT 4.4 to 35