2001 INFINITI QX4 Fuel

DTC Confirmation ProcedureNBEC0179NOTE:
If ªDTC Confirmation Procedureº has been previously conducted,
always turn ignition switch ªOFFº and wait at least 10 seconds
before conducting the next test.
SEF174Y
WITH CONSULT-IINBEC0179S011) Turn ignition switch ªONº.
2) Select ªDATA MONITORº mode with CONSULT-II.
3) Wait at least 10 seconds.
If the result is NG, go to ªDiagnostic Procedureº, EC-312.
If the result is OK, go to following step.
4) Check ªCOOLAN TEMP/Sº value.
If ªCOOLAN TEMP/Sº is less than 60ÉC (140ÉF), the result will
be OK.
If ªCOOLAN TEMP/Sº is above 60ÉC (140ÉF), go to the follow-
ing step.
5) Cool engine down until ªCOOLAN TEMP/Sº is less than 60ÉC
(140ÉF).
6) Wait at least 10 seconds.
7) If 1st trip DTC is detected, go to ªDiagnostic Procedureº,
EC-312.
WITH GSTNBEC0179S02Follow the procedure ªWith CONSULT-IIº above.
DTC P0180 FUEL TANK TEMPERATURE SENSOR
DTC Confirmation Procedure
EC-310

Wiring DiagramNBEC0180
MEC957C
GI
MA
EM
LC
FE
AT
TF
PD
AX
SU
BR
ST
RS
BT
HA
SC
EL
IDX
DTC P0180 FUEL TANK TEMPERATURE SENSOR
Wiring Diagram
EC-311

Diagnostic ProcedureNBEC0181
1 CHECK FUEL TANK TEMPERATURE SENSOR POWER SUPPLY CIRCUIT
1. Turn ignition switch ªOFFº.
2. Disconnect fuel level sensor unit and fuel pump harness connector.
SEF751UA
3. Turn ignition switch ªONº.
4. Check voltage between fuel level sensor unit terminal 1 and ground with CONSULT-II or tester.
SEF973Y
OK or NG
OK©GO TO 3.
NG©GO TO 2.
2 DETECT MALFUNCTIONING PART
Check the following.
IHarness connectors B1, M2
IHarness connectors M92, F27
IHarness for open or short between ECM and fuel level sensor unit and fuel pump
©Repair harness or connector.
3 CHECK FUEL TANK TEMPERATURE SENSOR GROUND CIRCUIT FOR OPEN AND SHORT
1. Turn ignition switch ªOFFº.
2. Check harness continuity between fuel level sensor unit and fuel pump terminal 2 and body ground. Refer to Wiring
Diagram.
Continuity should exist.
3. Also check harness for short to power.
OK or NG
OK©GO TO 4.
NG©Repair open circuit or short to power in harness or connectors.
DTC P0180 FUEL TANK TEMPERATURE SENSOR
Diagnostic Procedure
EC-312

4 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 5.
NG©Replace fuel level sensor unit.
5 CHECK INTERMITTENT INCIDENT
Refer to ªTROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENTº, EC-140.
©INSPECTION END
GI
MA
EM
LC
FE
AT
TF
PD
AX
SU
BR
ST
RS
BT
HA
SC
EL
IDX
DTC P0180 FUEL TANK TEMPERATURE SENSOR
Diagnostic Procedure (Cont'd)
EC-313

On Board Diagnosis LogicNBEC0182When a misfire occurs, engine speed will fluctuate. If the engine
speed fluctuates enough to cause the CKP sensor signal to vary,
ECM can determine that a misfire is occurring.
Sensor Input Signal to ECM ECM function
Crankshaft position sensor (POS) Engine speed On board diagnosis of misfire
The misfire detection logic consists of the following two conditions.
1. One Trip Detection Logic (Three Way Catalyst Damage)
On the first trip that a misfire condition occurs that can dam-
age the three way catalyst (TWC) due to overheating, the MIL
will blink.
When a misfire condition occurs, the ECM monitors the CKP
sensor signal every 200 engine revolutions for a change.
When the misfire condition decreases to a level that will not
damage the TWC, the MIL will turn off.
If another misfire condition occurs that can damage the TWC
on a second trip, the MIL will blink.
When the misfire condition decreases to a level that will not
damage the TWC, the MIL will remain on.
If another misfire condition occurs that can damage the TWC,
the MIL will begin to blink again.
2. Two Trip Detection Logic (Exhaust quality deterioration)
For misfire conditions that will not damage the TWC (but will
affect vehicle emissions), the MIL will only light when the mis-
fire is detected on a second trip. During this condition, the ECM
monitors the CKP sensor signal every 1,000 engine revolu-
tions.
A misfire malfunction can be detected on any one cylinder or
on multiple cylinders.
Malfunction is detected when multiple cylinders misfire, No. 1 cyl-
inder misfires, No. 2 cylinder misfires, No. 3 cylinder misfires, No.
4 cylinder misfires, No. 5 cylinder misfires and No. 6 cylinder
misfires.
Possible CauseNBEC0490IImproper spark plug
IInsufficient compression
IIncorrect fuel pressure
IThe injector circuit is open or shorted
IInjectors
IIntake air leak
IThe ignition secondary circuit is open or shorted
ILack of fuel
IDrive plate or flywheel
IHeated oxygen sensor 1 (front)
DTC P0300 - P0306 NO.6-1CYLINDER MISFIRE, MULTIPLE CYLINDER
MISFIRE
On Board Diagnosis Logic
EC-320

8 CHECK FUEL PRESSURE
1. Install all removed parts.
2. Release fuel pressure to zero. Refer to EC-39.
3. Install fuel pressure gauge and check fuel pressure. Refer to EC-39.
At idle:
Approx. 235 kPa (2.4 kg/cm
2, 34 psi)
OK or NG
OK©GO TO 10.
NG©GO TO 9.
9 DETECT MALFUNCTIONING PART
Check the following.
IFuel pump and circuit (Refer to EC-625.)
IFuel pressure regulator (Refer to EC-40.)
IFuel lines (Refer to MA-16, ªChecking Fuel Linesº.)
IFuel filter for clogging
©Repair or replace.
10 CHECK IGNITION TIMING
Check the following items. Refer to ªBasic Inspectionº, EC-101.
MTBL0655
OK or NG
OK (With CONSULT-II)©GO TO 11.
OK (Without CONSULT-
II)©GO TO 12.
NG©Follow the ªBasic Inspectionº.
DTC P0300 - P0306 NO.6-1CYLINDER MISFIRE, MULTIPLE CYLINDER
MISFIRE
Diagnostic Procedure (Cont'd)
EC-324

6 CHECK IGNITION SPARK
1. Turn ignition switch ªOFFº.
2. Disconnect ignition coil assembly from rocker cover.
3. Connect a known good spark plug to the ignition coil assembly.
4. Place end of spark plug against a suitable ground and crank engine.
5. Check for spark.
SEF575Q
OK or NG
OK©GO TO 7.
NG©Check ignition coil with power transistor and their circuit. Refer to EC-499.
7 CHECK INJECTOR
1. Turn ignition switch ªOFFº.
2. Remove injector assembly.
Refer to EC-41.
Keep fuel hose and all injectors connected to injector gallery.
3. Disconnect all ignition coil harness connectors.
4. Turn ignition switch ªONº.
Make sure fuel does not drip from injector.
OK or NG
OK (Does not drip.)©GO TO 8.
NG (Drips.)©Replace the injector(s) from which fuel is dripping.
8 CHECK INTERMITTENT INCIDENT
Refer to ªTROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENTº, EC-140.
Trouble is fixed.©INSPECTION END
Trouble is not fixed.©Replace warm-up three way catalyst.
GI
MA
EM
LC
FE
AT
TF
PD
AX
SU
BR
ST
RS
BT
HA
SC
EL
IDX
DTC P0420 (RIGHT BANK, -B1), P0430 (LEFT BANK, -B2) THREE WAY
CATALYST FUNCTION
Diagnostic Procedure (Cont'd)
EC-351

On Board Diagnosis LogicNBEC0218NOTE:
If DTC P0440 is displayed with P1448, perform trouble diagno-
sis for DTC P1448 first. (See EC-573.)
This diagnosis detects leaks in the EVAP purge line using engine
intake manifold vacuum.
If pressure does not increase, the ECM will check for leaks in the
line between the fuel tank and EVAP canister purge volume con-
trol solenoid valve, under the following ªVacuum testº conditions.
The vacuum cut valve bypass valve is opened to clear the line
between the fuel tank and the EVAP canister purge volume control
solenoid valve. The EVAP canister vent control valve will then be
closed to shut the EVAP purge line off. The EVAP canister purge
volume control solenoid valve is opened to depressurize the EVAP
purge line using intake manifold vacuum. After this occurs, the
EVAP canister purge volume control solenoid valve will be closed.
SEF373Z
Malfunction is detected when EVAP control system has a leak,
EVAP control system does not operate properly.
CAUTION:
IUse only a genuine NISSAN fuel filler cap as a replace-
ment. If an incorrect fuel filler cap is used, the MIL may
come on.
IIf the fuel filler cap is not tightened properly, the MIL may
come on.
IUse only a genuine NISSAN rubber tube as a replacement.
Possible CauseNBEC0510IIncorrect fuel tank vacuum relief valve
IIncorrect fuel filler cap used
IFuel filler cap remains open or fails to close.
IForeign matter caught in fuel filler cap.
ILeak is in line between intake manifold and EVAP canister
purge volume control solenoid valve.
IForeign matter caught in EVAP canister vent control valve.
IEVAP canister or fuel tank leaks
IEVAP purge line (pipe and rubber tube) leaks
DTC P0440 EVAP CONTROL SYSTEM (SMALL LEAK) (NEGATIVE PRESSURE)
On Board Diagnosis Logic
EC-352