2001 INFINITI QX4 Fuel

IEVAP purge line rubber tube bent.
IBlocked or bent rubber tube to EVAP control system pressure
sensor
ILoose or disconnected rubber tube
IEVAP canister vent control valve and the circuit
IEVAP canister purge volume control solenoid valve and the
circuit
IAbsolute pressure sensor
IFuel tank temperature sensor
IO-ring of EVAP canister vent control valve is missing or dam-
aged.
IWater separator
IEVAP canister is saturated with water.
IEVAP control system pressure sensor
IFuel level sensor and the circuit
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DTC P0440 EVAP CONTROL SYSTEM (SMALL LEAK) (NEGATIVE PRESSURE)
Possible Cause (Cont'd)
EC-353

SEF565X
DTC Confirmation ProcedureNBEC0219
SEF566X
SEF874X
SEF567X
NOTE:
IIf DTC P0440 or P1440 is displayed with P1448, perform
trouble diagnosis for DTC P1448 first. (See EC-573.)
IIf ªDTC Confirmation Procedureº has been previously
conducted, always turn ignition switch ªOFFº and wait at least
10 seconds before conducting the next test.
TESTING CONDITION:
IPerform ªDTC WORK SUPPORTº when the fuel level is
between 1/4 to 3/4 full and vehicle is placed on flat level
surface.
IOpen engine hood before conducting the following proce-
dure.
WITH CONSULT-IINBEC0219S011) Turn ignition switch ªONº.
2) Turn ignition switch ªOFFº and wait at least 10 seconds.
3) Turn ignition switch ªONº and select ªDATA MONITORº mode
with CONSULT-II.
4) Make sure that the following conditions are met.
COOLAN TEMP/S: 0 - 70ÉC (32 - 158ÉF)
INT/A TEMP SE: 0 - 30ÉC (32 - 86ÉF)
5) Select ªEVAP SML LEAK P0440/P1440º of ªEVAPORATIVE
SYSTEMº in ªDTC WORK SUPPORTº mode with CONSULT-
II.
Follow the instruction displayed.
NOTE:
If the engine speed cannot be maintained within the range dis-
played on the CONSULT-II screen, go to ªBasic Inspectionº,
EC-101.
6) Make sure that ªOKº is displayed.
If ªNGº is displayed, refer to ªDiagnostic Procedureº, EC-355.
NOTE:
Make sure that EVAP hoses are connected to EVAP canister
purge volume control solenoid valve properly.
WITH GSTNBEC0219S02NOTE:
Be sure to read the explanation of ªDriving Patternº on EC-66
before driving vehicle.
1) Start engine.
2) Drive vehicle according to ªDriving Patternº, EC-66.
3) Stop vehicle.
4) Select ªMODE 1º with GST.
IIf SRT of EVAP system is not set yet, go to the following step.
IIf SRT of EVAP system is set, the result will be OK.
5) Turn ignition switch ªOFFº and wait at least 10 seconds.
6) Start engine.
It is not necessary to cool engine down before driving.
7) Drive vehicle again according to the ªDriving Patternº, EC-66.
8) Stop vehicle.
9) Select ªMODE 3º with GST.
IIf P0440 or P1440 is displayed on the screen, go to ªDiagnos-
tic Procedureº, EC-355.
IIf P1447 is displayed on the screen, go to ªDiagnostic Proce-
dureº for DTC P1447, EC-564.
DTC P0440 EVAP CONTROL SYSTEM (SMALL LEAK) (NEGATIVE PRESSURE)
DTC Confirmation Procedure
EC-354

IIf P0440, P1440 and P1447 are not displayed on the screen,
go to the following step.
10) Select ªMODE 1º with GST.
IIf SRT of EVAP system is set, the result will be OK.
IIf SRT of EVAP system is not set, go to step 6.
Diagnostic ProcedureNBEC0220
1 CHECK FUEL FILLER CAP DESIGN
1. Turn ignition switch ªOFFº.
2. Check for genuine NISSAN fuel filler cap design.
SEF915U
OK or NG
OK©GO TO 2.
NG©Replace with genuine NISSAN fuel filler cap.
2 CHECK FUEL FILLER CAP INSTALLATION
Check that the cap is tightened properly by rotating the cap clockwise.
OK or NG
OK©GO TO 3.
NG©IOpen fuel filler cap, then clean cap and fuel filler neck threads using air blower.
IRetighten until ratcheting sound is heard.
3 CHECK FUEL FILLER CAP FUNCTION
Check for air releasing sound while opening the fuel filler cap.
OK or NG
OK©GO TO 5.
NG©GO TO 4.
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DTC P0440 EVAP CONTROL SYSTEM (SMALL LEAK) (NEGATIVE PRESSURE)
DTC Confirmation Procedure (Cont'd)
EC-355

4 CHECK FUEL TANK VACUUM RELIEF VALVE
1. Wipe clean valve housing.
2. Check valve opening pressure and vacuum.
SEF427N
SEF943S
Pressure:
15.3 - 20.0 kPa (0.156 - 0.204 kg/cm2, 2.22 - 2.90 psi)
Vacuum:
þ6.0 to þ3.3 kPa (þ0.061 to þ0.034 kg/cm
2, þ0.87 to þ0.48 psi)
CAUTION:
Use only a genuine fuel filler cap as a replacement. If an incorrect fuel filler cap is used, the MIL may come on.
OK or NG
OK©GO TO 5.
NG©Replace fuel filler cap with a genuine one.
DTC P0440 EVAP CONTROL SYSTEM (SMALL LEAK) (NEGATIVE PRESSURE)
Diagnostic Procedure (Cont'd)
EC-356

18 CHECK ABSOLUTE PRESSURE SENSOR
1. Remove absolute pressure sensor with its harness connector connected.
SEF961Y
2. Remove hose from absolute pressure sensor.
3. Install a vacuum pump to absolute pressure sensor.
4. Turn ignition switch ªONº and check output voltage between ECM terminal 80 and engine ground under the following
conditions.
SEF300XA
CAUTION:
IAlways calibrate the vacuum pump gauge when using it.
IDo not apply below þ93.3 kPa (±700 mmHg, ±27.56 inHg) or over 101.3 kPa (760 mmHg, 29.92 inHg) of pressure.
OK or NG
OK©GO TO 19.
NG©Replace absolute pressure sensor.
19 CHECK FUEL TANK TEMPERATURE SENSOR
1. Remove fuel level sensor unit.
2. Check resistance between fuel level sensor unit and fuel pump terminals 1 and 2 by heating with hot water or heat gun
as shown in the figure.
SEF974Y
OK or NG
OK©GO TO 20.
NG©Replace fuel level sensor unit.
DTC P0440 EVAP CONTROL SYSTEM (SMALL LEAK) (NEGATIVE PRESSURE)
Diagnostic Procedure (Cont'd)
EC-364

20 CHECK EVAP CONTROL SYSTEM PRESSURE SENSOR
1. Remove EVAP control system pressure sensor with its harness connector connected.
CAUTION:
INever apply force to the air hole protector of the sensor if equipped.
SEF799W
2. Remove hose from EVAP control system pressure sensor.
3. Turn ignition switch ªONº.
4. Use pump to apply vacuum and pressure to EVAP control system pressure sensor as shown in figure.
CAUTION:
IAlways calibrate the vacuum pump gauge when using it.
IDo not apply below þ20 kPa (þ150 mmHg, þ5.91 inHg) or over 20 kPa (150 mmHg, 5.91 inHg) of pressure.
5. Check input voltage between ECM terminal 84 and ground.
SEF342X
CAUTION:
IDiscard and EVAP control system pressure sensor which has been dropped from a height of more than 0.5m
(19.7in) onto a hard surface such as a concrete floor; use a new one.
OK or NG
OK©GO TO 21.
NG©Replace EVAP control system pressure sensor.
21 CHECK EVAP PURGE LINE
Check EVAP purge line (pipe, rubber tube, fuel tank and EVAP canister) for cracks or improper connection.
Refer to ªEvaporative Emission Systemº, EC-32.
OK or NG
OK©GO TO 22.
NG©Repair or reconnect the hose.
22 CLEAN EVAP PURGE LINE
Clean EVAP purge line (pipe and rubber tube) using air blower.
©GO TO 23.
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DTC P0440 EVAP CONTROL SYSTEM (SMALL LEAK) (NEGATIVE PRESSURE)
Diagnostic Procedure (Cont'd)
EC-365

23 CHECK FUEL LEVEL SENSOR
Refer to EL-108, ªFuel Level Sensor Unit Checkº.
OK or NG
OK©GO TO 24.
NG©Replace fuel level sensor unit.
24 CHECK INTERMITTENT INCIDENT
Refer to ªTROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENTº, EC-140.
©INSPECTION END
DTC P0440 EVAP CONTROL SYSTEM (SMALL LEAK) (NEGATIVE PRESSURE)
Diagnostic Procedure (Cont'd)
EC-366

DescriptionNBEC0221SYSTEM DESCRIPTIONNBEC0221S01
Sensor Input Signal to ECMECM
functionActuator
Crankshaft position sensor (POS) Engine speed (POS signal)
EVAP can-
ister purge
flow controlEVAP canister purge volume
control solenoid valve Crankshaft position sensor (REF) Engine speed (REF signal)
Mass air flow sensor Amount of intake air
Engine coolant temperature sensor Engine coolant temperature
Ignition switch Start signal
Throttle position sensor Throttle position
Throttle position switch Closed throttle position
Heated oxygen sensor 1 (front)Density of oxygen in exhaust gas
(Mixture ratio feedback signal)
Fuel tank temperature sensor Fuel temperature in fuel tank
Vehicle speed sensor Vehicle speed
This system controls flow rate of fuel vapor from the EVAP canis-
ter. The opening of the vapor by-pass passage in the EVAP canis-
ter purge volume control solenoid valve changes to control the flow
rate. The EVAP canister purge volume control solenoid valve
repeats ON/OFF operation according to the signal sent from the
ECM. The opening of the valve varies for optimum engine control.
The optimum value stored in the ECM is determined by consider-
ing various engine conditions. When the engine is operating, the
flow rate of fuel vapor from the EVAP canister is regulated as the
air flow changes.
SEF337U
COMPONENT DESCRIPTIONNBEC0221S02The EVAP canister purge volume control solenoid valve uses a
ON/OFF duty to control the flow rate of fuel vapor from the EVAP
canister. The EVAP canister purge volume control solenoid valve
is moved by ON/OFF pulses from the ECM. The longer the ON
pulse, the greater the amount of fuel vapor that will flow through the
valve.
CONSULT-II Reference Value in Data Monitor
Mode
NBEC0222Specification data are reference values.
MONITOR ITEM CONDITION SPECIFICATION
PURG VOL C/VIEngine: After warming up
IAir conditioner switch ªOFFº
IShift lever: ªNº
INo-loadIdle (Vehicle stopped) 0%
2,000 rpm Ð
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DTC P0443 EVAP CANISTER PURGE VOLUME CONTROL SOLENOID VALVE
(CIRCUIT)
Description
EC-367