2005 INFINITI QX4 air condition

DTC P0101 MAF SENSOR
EC-181
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Revision: October 20052005 QX56
Component InspectionUBS00H12
MASS AIR FLOW SENSOR
With CONSULT-II
1. Reconnect all harness connectors disconnected.
2. Start engine and warm it up to normal operating temperature.
3. Connect CONSULT-II and select “DATA MONITOR” mode.
4. Select “MAS A/F SE-B1” and check indication under the follow-
ing conditions.
*: Check for linear voltage rise in response to engine being increased to about
4,000 rpm.
5. If the voltage is out of specification, proceed the following.
a. Check for the cause of uneven air flow through mass air flow sensor. Refer to following.

Crushed air ducts

Malfunctioning seal of air cleaner element

Uneven dirt of air cleaner element

Improper specification of intake air system parts
b. If NG, repair or replace malfunctioning part and perform step 2 to 4 again.
If OK, go to next step.
6. Turn ignition switch OFF.
7. Disconnect mass air flow sensor harness connector and reconnect it again.
8. Perform step 2 to 4 again.
9. If NG, clean or replace mass air flow sensor.
Without CONSULT-II
1. Reconnect all harness connectors disconnected.
2. Start engine and warm it up to normal operating temperature.
3. Check voltage between ECM terminal 51 (Mass air flow sensor
signal) and ground.
*: Check for linear voltage rise in response to engine being increased to about
4,000 rpm.
4. If the voltage is out of specification, proceed the following.
a. Check for the cause of uneven air flow through mass air flow sensor. Refer to following.

Crushed air ducts

Malfunctioning seal of air cleaner element

Uneven dirt of air cleaner element

Improper specification of intake air system parts
Condition MAS A/F SE-B1 (V)
Ignition switch ON (Engine stopped.) Approx. 0.4
Idle (Engine is warmed-up to normal
operating temperature.)1.0 - 1.3
2,500 rpm (Engine is warmed-up to
normal operating temperature.)1.7 - 2.1
Idle to about 4,000 rpm* 1.0 - 1.3 to Approx. 2.4
PBIB2371E
Condition MAS A/F SE-B1 (V)
Ignition switch ON (Engine stopped.) Approx. 0.4
Idle (Engine is warmed-up to normal
operating temperature.)1.0 - 1.3
2,500 rpm (Engine is warmed-up to
normal operating temperature.)1.7 - 2.1
Idle to about 4,000 rpm* 1.0 - 1.3 to Approx. 2.4
PBIB11 06 E

DTC P0102, P0103 MAF SENSOR
EC-183
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Revision: October 20052005 QX56
DTC P0102, P0103 MAF SENSORPFP:22680
Component DescriptionUBS00H14
The mass air flow sensor is placed in the stream of intake air. It mea-
sures the intake flow rate by measuring a part of the entire intake
flow. The mass air flow sensor controls the temperature of the hot
wire to a certain amount. The heat generated by the hot wire is
reduced as the intake air flows around it. The more air, the greater
the heat loss.
Therefore, the electric current supplied to the hot wire is changed to
maintain the temperature of the hot wire as air flow increases. The
ECM detects the air flow by means of this current change.
CONSULT-II Reference Value in Data Monitor ModeUBS00H15
Specification data are reference values.
On Board Diagnosis LogicUBS00H16
These self-diagnoses have the one trip detection logic.
FAIL-SAFE MODE
When the malfunction is detected, the ECM enters fail-safe mode and the MIL lights up.
BBIA0355E
MONITOR ITEM CONDITION SPECIFICATION
MAS A/F SE-B1 See EC-146, "
TROUBLE DIAGNOSIS - SPECIFICATION VALUE" .
CAL/LD VALUE

Engine: After warming up

Air conditioner switch: OFF

Selector lever: P or N

No loadIdle 14% - 33%
2,500 rpm 12% - 25%
MASS AIRFLOW

Engine: After warming up

Air conditioner switch: OFF

Selector lever: P or N

No loadIdle 3.0 - 9.0 g·m/s
2,500 rpm 9.0 - 28.0 g·m/s
DTC No. Trouble diagnosis name DTC detecting condition Possible cause
P0102
0102Mass air flow sensor circuit
low inputAn excessively low voltage from the sensor is
sent to ECM.

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

Intake air leaks

Mass air flow sensor
P0103
0103Mass air flow sensor circuit
high inputAn excessively high voltage from the sensor is
sent to ECM.

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

Mass air flow sensor
Detected items Engine operating condition in fail-safe mode
Mass air flow sensor circuit Engine speed will not rise more than 2,400 rpm due to the fuel cut.

EC-186Revision: October 2005
DTC P0102, P0103 MAF SENSOR
2005 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 ProcedureUBS00H19
1. INSPECTION START
Which malfunction (P0102 or P0103) is duplicated?
P0102 or P0103
P0102 >> GO TO 2.
P0103 >> GO TO 3.
2. CHECK INTAKE SYSTEM
Check the following for connection.

Air duct

Vacuum hoses

Intake air passage between air duct to intake manifold
OK or NG
OK >> GO TO 3.
NG >> Reconnect the parts.
TER-
MINAL
NO.WIRE
COLORITEM CONDITION DATA (DC Voltage)
51 W Mass air flow sensor[Engine is running]

Warm-up condition

Idle speed1.0 - 1.3V
[Engine is running]

Warm-up condition

Engine speed: 2,500 rpm.1.7 - 2.1V
67 B Sensor ground[Engine is running]

Warm-up condition

Idle speedApproximately 0V
111 W /BECM relay
(Self shut-off)[Engine is running]
[Ignition switch: OFF]

For a few seconds after turning ignition
switch OFF0 - 1.5V
[Ignition switch: OFF]

More than a few seconds after turning igni-
tion switch OFFBATTERY VOLTAGE
(11 - 14V)
11 9
120BR
BRPower supply for ECM[Ignition switch: ON]BATTERY VOLTAGE
(11 - 14V)

DTC P0102, P0103 MAF SENSOR
EC-189
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Revision: October 20052005 QX56
Component InspectionUBS00H1A
MASS AIR FLOW SENSOR
With CONSULT-II
1. Reconnect all harness connectors disconnected.
2. Start engine and warm it up to normal operating temperature.
3. Connect CONSULT-II and select “DATA MONITOR” mode.
4. Select “MAS A/F SE-B1” and check indication under the follow-
ing conditions.
*: Check for linear voltage rise in response to engine being increased to about
4,000 rpm.
5. If the voltage is out of specification, proceed the following.
a. Check for the cause of uneven air flow through mass air flow sensor. Refer to following.

Crushed air ducts

Malfunctioning seal of air cleaner element

Uneven dirt of air cleaner element

Improper specification of intake air system parts
b. If NG, repair or replace malfunctioning part and perform step 2 to 4 again.
If OK, go to next step.
6. Turn ignition switch OFF.
7. Disconnect mass air flow sensor harness connector and reconnect it again.
8. Perform step 2 to 4 again.
9. If NG, clean or replace mass air flow sensor.
Without CONSULT-II
1. Reconnect all harness connectors disconnected.
2. Start engine and warm it up to normal operating temperature.
3. Check voltage between ECM terminal 51 (Mass air flow sensor
signal) and ground.
*: Check for linear voltage rise in response to engine being increased to about
4,000 rpm.
4. If the voltage is out of specification, proceed the following.
a. Check for the cause of uneven air flow through mass air flow sensor. Refer to following.

Crushed air ducts

Malfunctioning seal of air cleaner element

Uneven dirt of air cleaner element

Improper specification of intake air system parts
Condition MAS A/F SE-B1 (V)
Ignition switch ON (Engine stopped.) Approx. 0.4
Idle (Engine is warmed-up to normal
operating temperature.)1.0 - 1.3
2,500 rpm (Engine is warmed-up to
normal operating temperature.)1.7 - 2.1
Idle to about 4,000 rpm* 1.0 - 1.3 to Approx. 2.4
PBIB2371E
Condition MAS A/F SE-B1 (V)
Ignition switch ON (Engine stopped.) Approx. 0.4
Idle (Engine is warmed-up to normal
operating temperature.)1.0 - 1.3
2,500 rpm (Engine is warmed-up to
normal operating temperature.)1.7 - 2.1
Idle to about 4,000 rpm* 1.0 - 1.3 to Approx. 2.4
PBIB11 06 E

DTC P0112, P0113 IAT SENSOR
EC-191
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Revision: October 20052005 QX56
DTC P0112, P0113 IAT SENSORPFP:22630
Component DescriptionUBS00H1C
The intake air temperature sensor is built-into mass air flow sensor.
The sensor detects intake air temperature and transmits a signal to
the ECM.
The temperature sensing unit uses a thermistor which is sensitive to
the change in temperature. Electrical resistance of the thermistor
decreases in response to the temperature rise.

*: This data is reference value and is measured between ECM terminal 34 (Intake air
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 LogicUBS00H1D
DTC Confirmation ProcedureUBS00H1E
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 5 seconds.
4. If 1st trip DTC is detected, go to EC-193, "
Diagnostic Procedure"
.
WITH GST
Follow the procedure “WITH CONSULT-II” above.
BBIA0355E
Intake air temperature
°C (°F)Voltage* V Resistance kΩ
25 (77) 3.32 1.94 - 2.06
80 (176) 1.23 0.295 - 0.349
SEF 0 12 P
DTC No. Trouble diagnosis name DTC detecting condition Possible cause
P0112
0112Intake air temperature
sensor circuit low inputAn excessively low voltage from the sensor is
sent to ECM.

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

Intake air temperature sensor P0113
0113Intake air temperature
sensor circuit high inputAn excessively high voltage from the sensor is
sent to ECM.
SEF 0 58 Y

EC-194Revision: October 2005
DTC P0112, P0113 IAT SENSOR
2005 QX56
3. CHECK INTAKE AIR TEMPERATURE SENSOR GROUND CIRCUIT FOR OPEN AND SHORT
1. Turn ignition switch OFF.
2. Disconnect ECM harness connector.
3. Check harness continuity between mass air flow sensor terminal 6 and ECM terminal 67.
Refer to Wiring Diagram.
4. Also check harness for short to ground and short to power.
OK or NG
OK >> GO TO 4.
NG >> Repair open circuit or short to ground or short to power in harness or connectors.
4. CHECK INTAKE AIR TEMPERATURE SENSOR
Refer to EC-194, "
Component Inspection" .
OK or NG
OK >> GO TO 5.
NG >> Replace mass air flow sensor (with intake air temperature sensor).
5. CHECK INTERMITTENT INCIDENT
Refer to EC-156, "
TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT" .
>>INSPECTION END
Component InspectionUBS00H1H
INTAKE AIR TEMPERATURE SENSOR
1. Check resistance between mass air flow sensor terminals 5 and
6 under the following conditions.
2. If NG, replace mass air flow sensor (with intake air temperature
sensor).
Removal and InstallationUBS00H1I
MASS AIR FLOW SENSOR
Refer to EM-14, "AIR CLEANER AND AIR DUCT" . Continuity should exist.
Intake air temperature °C (°F) Resistance kΩ
25 (77) 1.94 - 2.06
BBIA0355E
SEF 0 12 P

EC-204Revision: October 2005
DTC P0122, P0123 TP SENSOR
2005 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 ProcedureUBS00H1V
1. CHECK GROUND CONNECTIONS
1. Turn ignition switch OFF.
2. Loosen and retighten three ground screws on the body.
Refer to EC-162, "
Ground Inspection" .
OK or NG
OK >> GO TO 2.
NG >> Repair or replace ground connections.
TER-
MINAL
NO.WIRE
COLORITEM 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

Selector lever: D

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

Engine: Stopped

Selector 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

Selector lever: D

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

Engine: Stopped

Selector ever: D

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

EC-210Revision: October 2005
DTC P0125 ECT SENSOR
2005 QX56
3. CHECK THERMOSTAT OPERATION
When the engine is cold [lower than 70°C (158°F)] condition, grasp lower radiator hose and confirm the engine
coolant does not flow.
OK or NG
OK >> GO TO 4.
NG >> Repair or replace thermostat. Refer to CO-19, "
THERMOSTAT AND WATER PIPING" .
4. CHECK INTERMITTENT INCIDENT
Refer to EC-156, "
TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT" .
Refer to EC-197, "
Wiring Diagram" .
>>INSPECTION END
Component InspectionUBS00H22
ENGINE COOLANT TEMPERATURE SENSOR
1. Check resistance between engine coolant temperature sensor
terminals 1 and 2 as shown in the figure.

2. If NG, replace engine coolant temperature sensor.
Removal and InstallationUBS00H23
ENGINE COOLANT TEMPERATURE SENSOR
Refer to CO-19, "THERMOSTAT AND WATER PIPING" .
PBIB2005E
Engine coolant temperature°C (°F) Resistance kΩ
20 (68) 2.1 - 2.9
50 (122) 0.68 - 1.00
90 (194) 0.236 - 0.260
SEF 0 12 P