2004 INFINITI QX56 check engine

DTC P0172, P0175 FUEL INJECTION SYSTEM FUNCTION
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Revision: August 20072004 QX56
4. CHECK FUEL PRESSURE
1. Release fuel pressure to zero. Refer to EC-46, "
FUEL PRESSURE RELEASE" .
2. Install fuel pressure gauge and check fuel pressure. Refer to EC-47, "
FUEL PRESSURE CHECK" .
OK or NG
OK >> GO TO 6.
NG >> GO TO 5.
5. DETECT MALFUNCTIONING PART
Check the following.

Fuel pump and circuit (Refer to, EC-601, "FUEL PUMP CIRCUIT" .)

Fuel pressure regulator (Refer to EC-47, "FUEL PRESSURE CHECK" .)
>> Repair or replace.
6. CHECK MASS AIR FLOW SENSOR
With CONSULT-II
1. Install all removed parts.
2. Check “MASS AIR FLOW” in “DATA MONITOR” mode with CONSULT-II.
With GST
1. Install all removed parts.
2. Check mass air flow sensor signal in MODE 1 with GST.
OK or NG
OK >> GO TO 7.
NG >> Check connectors for rusted terminals or loose connections in the mass air flow sensor circuit or
engine grounds. Refer to EC-146, "
DTC P0101 MAF SENSOR" . At idling: 350 kPa (3.57 kg/cm
2 , 51 psi)
3.0 - 9.0 g·m/sec: at idling
9.0 - 28.0 g·m/sec: at 2,500 rpm
3.0 - 9.0 g·m/sec: at idling
9.0 - 28.0 g·m/sec: at 2,500 rpm

EC-224Revision: August 2007
DTC P0172, P0175 FUEL INJECTION SYSTEM FUNCTION
2004 QX56
7. CHECK FUNCTION OF INJECTORS
With CONSULT-II
1. Start engine.
2. Perform “POWER BALANCE” in “ACTIVE TEST” mode with
CONSULT-II.
3. Make sure that each circuit produces a momentary engine
speed drop.
Without CONSULT-II
1. Start engine.
2. Listen to each injector operating sound.
OK or NG
OK >> GO TO 8.
NG >> Perform trouble diagnosis for EC-595, "
INJECTOR CIRCUIT" .
8. CHECK INJECTOR
1. Remove injector assembly. Refer to EM-29, "
FUEL INJECTOR AND FUEL TUBE" .
Keep fuel hose and all injectors connected to injector gallery.
2. Confirm that the engine is cooled down and there are no fire hazards near the vehicle.
3. Disconnect all injector harness connectors.
4. Disconnect all ignition coil harness connectors.
5. Prepare pans or saucers under each injectors.
6. Crank engine for about 3 seconds.
Make sure fuel does not drip from injector.
OK or NG
OK (Does not drip.)>>GO TO 9.
NG (Drips.)>>Replace the injectors from which fuel is dripping. Always replace O-ring with new one.
9. CHECK INTERMITTENT INCIDENT
Refer to EC-127, "
TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT" .
>>INSPECTION END
PBIB0133E
Clicking noise should be heard.
PBIB1986E

DTC P0181 FTT SENSOR
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Revision: August 20072004 QX56
DTC P0181 FTT SENSORPFP:22630
Component DescriptionUBS00H34
The fuel tank temperature sensor is used to detect the fuel tempera-
ture inside the fuel tank. The sensor modifies a voltage signal from
the ECM. The modified signal returns to the ECM as the fuel temper-
ature input. The sensor uses a thermistor which is sensitive to the
change in temperature. The electrical resistance of the thermistor
decreases as temperature increases.

*: This data is reference value and is measured between ECM terminal 107 (Fuel
tank temperature sensor) and ground.
CAUTION:
Do not use ECM ground terminals when measuring input/output
voltage. Doing so may result in damage to the ECM's transistor.
Use a ground other than ECM terminals, such as the ground.
On Board Diagnosis LogicUBS00H35
DTC Confirmation ProcedureUBS00H36
NOTE:
If DTC Confirmation Procedure has been previously conducted, always turn ignition switch OFF and wait at
least 10 seconds before conducting the next test.
WITH CONSULT-II
1. Turn ignition switch ON.
2. Select “DATA MONITOR” mode with CONSULT-II.
3. Wait at least 10 seconds.
If the result is NG, go to EC-228, "
Diagnostic Procedure" .
If the result is OK, go to following step.
4. Check “COOLAN TEMP/S” value.
If “COOLAN TEMP/S” is less than 60°C (140°F), the result will
be OK.
If “COOLAN TEMP/S” is above 60°C (140°F), go to the following
step.
5. Cool engine down until “COOLAN TEMP/S” is less than 60°C
(140°F).
6. Wait at least 10 seconds.
7. If 1st trip DTC is detected, go to EC-228, "
Diagnostic Procedure" .
BBIA0583E
Fluid temperature
°C (°F)Voltage*
VResistance
kΩ
20 (68) 3.5 2.3 - 2.7
50 (122) 2.2 0.79 - 0.90
SEF 0 12 P
DTC No. Trouble diagnosis name DTC detecting condition Possible cause
P0181
0181Fuel tank temperature
sensor circuit range/
performanceRationally incorrect voltage from the sensor is
sent to ECM, compared with the voltage sig-
nals from engine coolant temperature sensor
and intake air temperature sensor.

Harness or connectors
(The sensor circuit is open or shorted)

Fuel tank temperature sensor
SEF 1 74 Y

DTC P0222, P0223 TP SENSOR
EC-239
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Revision: August 20072004 QX56
Specification data are reference values and are measured between each terminal and ground.
CAUTION:
Do not use ECM ground terminals when measuring input/output voltage. Doing so may result in dam-
age to the ECM's transistor. Use a ground other than ECM terminals, such as the ground.
Diagnostic ProcedureUBS00H3N
1. CHECK GROUND CONNECTIONS
1. Turn ignition switch OFF.
2. Loosen and retighten three ground screws on the body.
Refer to EC-133, "
Ground Inspection" .
OK or NG
OK >> GO TO 2.
NG >> Repair or replace ground connections.
TER-
MINAL
NO.WIRE
COLOR ITEM CONDITION DATA (DC Voltage)
47 YSensor power supply
(Throttle position sensor)[Ignition switch: ON]Approximately 5V
50 B Throttle position sensor 1[Ignition switch: ON]

Engine stopped

Shift lever: D

Accelerator pedal: Fully releasedMore than 0.36V
[Ignition switch: ON]

Engine stopped

Shift lever: D

Accelerator pedal: Fully depressedLess than 4.75V
66 RSensor ground
(Throttle position sensor)[Engine is running]

Warm-up condition

Idle speedApproximately 0V
69 W Throttle position sensor 2[Ignition switch: ON]

Engine stopped

Shift lever: D

Accelerator pedal: Fully releasedLess than 4.75V
[Ignition switch: ON]

Engine stopped

Shift lever: D

Accelerator pedal: Fully depressedMore than 0.36V
91 W/RSensor power supply
(APP sensor 2)[Ignition switch: ON]Approximately 5V
BBIA0354E

EC-244Revision: August 2007
DTC P0300 - P0308 MULTIPLE CYLINDER MISFIRE, NO. 1 - 8 CYLINDER MIS-
FIRE
2004 QX56
WITH CONSULT-II
1. Turn ignition switch ON, and select “DATA MONITOR” mode
with CONSULT-II.
2. Start engine and warm it up to normal operating temperature.
3. Turn ignition switch OFF and wait at least 10 seconds.
4. Restart engine and let it idle for about 15 minutes.
5. If 1st trip DTC is detected, go to EC-244, "
Diagnostic Procedure"
.
NOTE:
If 1st trip DTC is not detected during above procedure, performing
the following procedure is advised.
1. Turn ignition switch OFF and wait at least 10 seconds.
2. Start engine and drive the vehicle under the similar conditions to (1st trip) Freeze Frame Data for a certain
time. Refer to the table below.
Hold the accelerator pedal as steady as possible.
The similar conditions to (1st trip) Freeze Frame Data means the vehicle operation that the following con-
ditions should be satisfied at the same time.
The time to driving varies according to the engine speed in the freeze frame data.
WITH GST
Follow the procedure “WITH CONSULT-II” above.
Diagnostic ProcedureUBS00H3S
1. CHECK FOR INTAKE AIR LEAK AND PCV HOSE
1. Start engine and run it at idle speed.
2. Listen for the sound of the intake air leak.
3. Check PCV hose connection.
OK or NG
OK >> GO TO 2.
NG >> Discover air leak location and repair.
2. CHECK FOR EXHAUST SYSTEM CLOGGING
Stop engine and visually check exhaust tube, three way catalyst and muffler for dents.
OK or NG
OK >> GO TO 3.
NG >> Repair or replace it.
PBIB0164E
Engine speed Engine speed in the freeze frame data ± 400 rpm
Vehicle speed Vehicle speed in the freeze frame data ± 10 km/h (6 MPH)
Engine coolant temperature
(T) conditionWhen the freeze frame data shows lower than 70 °C (158 °F),
T should be lower than 70 °C (158 °F).
When the freeze frame data shows higher than or equal to 70 °C (158 °F),
T should be higher than or equal to 70 °C (158 °F).
Engine speed Time
Around 1,000 rpm Approximately 10 minutes
Around 2,000 rpm Approximately 5 minutes
More than 3,000 rpm Approximately 3.5 minutes

DTC P0300 - P0308 MULTIPLE CYLINDER MISFIRE, NO. 1 - 8 CYLINDER MIS-
FIRE
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Revision: August 20072004 QX56
3. PERFORM POWER BALANCE TEST
With CONSULT-II
1. Perform “POWER BALANCE” in “ACTIVE TEST” mode.
2. Is there any cylinder which does not produce a momentary
engine speed drop?
Without CONSULT-II
When disconnecting each injector harness connector one at a time, is there any cylinder which does not pro-
duce a momentary engine speed drop?
Ye s o r N o
Yes >> GO TO 4.
No >> GO TO 7.
4. CHECK INJECTOR
Does each injector make an operating sound at idle?
Ye s o r N o
Yes >> GO TO 5.
No >> Check injector(s) and circuit(s). Refer to EC-595,
"INJECTOR CIRCUIT" .
PBIB0133E
BBIA0374E
PBIB1986E

EC-246Revision: August 2007
DTC P0300 - P0308 MULTIPLE CYLINDER MISFIRE, NO. 1 - 8 CYLINDER MIS-
FIRE
2004 QX56
5. CHECK IGNITION SPARK
1. Turn ignition switch OFF.
2. Remove ignition coil assembly from rocker cover.
3. Remove spark plug from ignition coil assembly.
4. Connect a known-good spark plug to the ignition coil.
5. Disconnect all injector harness connectors.
6. Place end of spark plug against a suitable ground and crank engine.
7. Check for spark.
OK or NG
OK >> GO TO 6.
NG >> Check ignition coil, power transistor and their circuits.
Refer to EC-583, "
IGNITION SIGNAL" .
6. CHECK SPARK PLUGS
Remove the spark plugs and check for fouling, etc.
OK or NG
OK >> GO TO 7.
NG >> Repair or replace spark plug(s) with standard type
one(s). For spark plug type, refer to MA-17, "
Changing
Spark Plugs" .
7. CHECK COMPRESSION PRESSURE
Check compression pressure. Refer to EM-59, "
CHECKING COMPRESSION PRESSURE" .
OK or NG
OK >> GO TO 8.
NG >> Check pistons, piston rings, valves, valve seats and cylinder head gaskets.
SEF 5 75 Q
SEF 1 56 I
Standard:
1,520 kPa (15.5 kg/cm2 , 220 psi)/200 rpm
Minimum:
1,324 kPa (13.5 kg/cm
2 , 192 psi)/200 rpm
Difference between each
cylinder:98 kPa (1.0 kg/cm
2 , 14 psi)/200 rpm

DTC P0300 - P0308 MULTIPLE CYLINDER MISFIRE, NO. 1 - 8 CYLINDER MIS-
FIRE
EC-249
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Revision: August 20072004 QX56
13. CHECK MASS AIR FLOW SENSOR
With CONSULT-II
Check mass air flow sensor signal in “DATA MONITOR” mode with CONSULT-II.
With GST
Check mass air flow sensor signal in MODE 1 with GST.
OK or NG
OK >> GO TO 14.
NG >> Check connectors for rusted terminals or loose connections in the mass air flow sensor circuit or
engine grounds. Refer to EC-146, "
DTC P0101 MAF SENSOR" .
14. CHECK SYMPTOM MATRIX CHART
Check items on the rough idle symptom in EC-84, "
Symptom Matrix Chart" .
OK or NG
OK >> GO TO 15.
NG >> Repair or replace.
15. ERASE THE 1ST TRIP DTC
Some tests may cause a 1st trip DTC to be set.
Erase the 1st trip DTC from the ECM memory after performing the tests. Refer to EC-62, "
HOW TO ERASE
EMISSION-RELATED DIAGNOSTIC INFORMATION" .
>> GO TO 16.
16. CHECK INTERMITTENT INCIDENT
Refer to EC-127, "
TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT" .
>>INSPECTION END 3.0 - 9.0 g·m/sec: at idling
9.0 - 28.0 g·m/sec: at 2,500 rpm
3.0 - 9.0 g·m/sec: at idling
9.0 - 28.0 g·m/sec: at 2,500 rpm