ESP INFINITI QX56 2006 Factory Repair Manual

DTC P0139, P0159 HO2S2EC-277
C
DE
F
G H
I
J
K L
M A
EC
Revision: November 2009 2006 QX56
DTC P0139, P0159 HO2S2PFP:226A0
Component DescriptionUBS00H2N
The heated oxygen sensor 2, after three way catalyst (manifold),
monitors the oxygen level in the exhaust gas on each bank.
Even if switching characteristics of the air fuel ratio (A/F) sensor 1
are shifted, the air-fuel ratio is controlled to stoichiometric, by the sig-
nal from the heated oxygen sensor 2.
This sensor is made of ceramic zirconia. The zirconia generates volt-
age from approximately 1V in richer conditions to 0V in leaner condi-
tions.
Under normal conditions the heated oxygen sensor 2 is not used for
engine control operation.
CONSULT-II Reference Value in Data Monitor ModeUBS00H2O
Specification data are reference values.
On Board Diagnosis LogicUBS00H2P
The heated oxygen sensor 2 has a much longer switching time
between rich and lean than the air fuel ratio (A/F) sensor 1. The oxy-
gen storage capacity of the three way catalyst (manifold) causes the
longer switching time. To judge the malfunctions of heated oxygen
sensor 2, ECM monitors whether the switching response of the sen-
sor's voltage is faster than specified during the various driving condi-
tion such as fuel-cut.
SEF327R
MONITOR ITEMCONDITION SPECIFICATION
HO2S2 (B1)
HO2S2 (B2)

Revving engine from idle to 3,000 rpm quickly after the following condi-
tions are met.
–Engine: After warming up
–Keeping the engine speed between 3,500 and 4,000 rpm for 1 minute and
at idle for 1 minute under no load 0 - 0.3V
←→ Approx. 0.6 -
1.0V
HO2S2 MNTR (B1)
HO2S2 MNTR (B2) LEAN
←→ RICH
SEF302U
DTC No. Trouble diagnosis name DTC detecting condition Possible cause
P0139
0139
(Bank 1) Heated oxygen sensor
2 circuit slow response It takes more time for the sensor to respond
between rich and lean than the specified time.

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

Heated oxygen sensor 2

Fuel pressure

Fuel injector

Intake air leaks
P0159
0159
(Bank 2)

DTC P0171, P0174 FUEL INJECTION SYSTEM FUNCTIONEC-295
C
DE
F
G H
I
J
K L
M A
EC
Revision: November 2009 2006 QX56
3. CHECK A/F SENSOR 1 INPUT SIGNAL CIRCUIT
1. Turn ignition switch OFF.
2. Disconnect corresponding A/F sensor 1 harness connector.
3. Disconnect ECM harness connector.
4. Check harness continuity between the following terminals. Refer to Wiring Diagram.
5. Check harness continuity between the following terminals and ground. Refer to Wiring Diagram.
6. Also check harness for 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.
A/F sensor 1 terminal ECM terminal
Bank 1 11
6
27 5
53 5
65 6
Bank 2 17
6
27 7
55 7
65 8
Continuity should exist.
Bank 1 Bank 2
A/F sensor 1 terminal ECM terminal A/F sensor 1 terminal ECM terminal 11 617 6
27 527 7
53 555 7
65 665 8
Continuity should not exist.
BBIA0376E

EC-306Revision: November 2009
DTC P0172, P0175 FUEL INJECTION SYSTEM FUNCTION
2006 QX56
3. CHECK A/F SENSOR 1 INPUT SIGNAL CIRCUIT
1. Turn ignition switch OFF.
2. Disconnect corresponding A/F sensor 1 harness connector.
3. Disconnect ECM harness connector.
4. Check harness continuity between the following terminals. Refer to Wiring Diagram.
5. Check harness continuity between the following terminals and ground. Refer to Wiring Diagram.
6. Also check harness for 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.
A/F sensor 1 terminal ECM terminal
Bank 1 11
6
27 5
53 5
65 6
Bank 2 17
6
27 7
55 7
65 8
Continuity should exist.
Bank 1 Bank 2
A/F sensor 1 terminal ECM terminal A/F sensor 1 terminal ECM terminal 11 617 6
27 527 7
53 555 7
65 665 8
Continuity should not exist.
BBIA0376E

EC-320Revision: November 2009
DTC P0222, P0223 TP SENSOR
2006 QX56
DTC P0222, P0223 TP SENSORPFP:16119
Component DescriptionUBS00H3I
Electric throttle control actuator consists of throttle control motor,
throttle position sensor, etc. The throttle position sensor responds to
the throttle valve movement.
The throttle position sensor has the two sensors. These sensors are
a kind of potentiometers which transform the throttle valve position
into output voltage, and emit the voltage signal to the ECM. In addi-
tion, these sensors detect the opening and closing speed of the
throttle valve and feed the voltage signals to the ECM. The ECM
judges the current opening angle of the throttle valve from these sig-
nals and the ECM controls the throttle control motor to make the
throttle valve opening angle properly in response to driving condi-
tion.
CONSULT-II Reference Value in Data Monitor ModeUBS00H3J
Specification data are reference values.
*: Throttle position sensor 2 signal is converted by ECM internally. Thus, it differs from ECM terminal voltage signal.
On Board Diagnosis LogicUBS00H3K
These self-diagnoses have the one trip detection logic.
FAIL-SAFE MODE
When the malfunction is detected, ECM enters fail-safe mode and the MIL lights up.
PBIB0145E
MONITOR ITEMCONDITION SPECIFICATION
THRTL SEN 1
THRTL SEN 2*

Ignition switch: ON
(Engine stopped)

Selector lever: D Accelerator pedal: Fully released More than 0.36V
Accelerator pedal: Fully depressed Less than 4.75V
DTC No. Trouble diagnosis name
DTC detecting condition Possible cause
P0222
0222 Throttle position sensor
1 circuit low input An excessively low voltage from the TP sensor
1 is sent to ECM.

Harness or connectors
(TP sensor 1 circuit is open or shorted.)
(APP sensor 2 circuit is shorted.)

Electric throttle control actuator
(TP sensor 1)

Accelerator pedal position sensor
(APP sensor 2)
P0223
0223
Throttle position sensor
1 circuit high input An excessively high voltage from the TP sensor
1 is sent to ECM.
Engine operation condition in fail-safe mode
The ECM controls the electric throttle control actuator in regulating the throttle opening in order for the idle position to be within +10
degrees.
The ECM regulates the opening speed of the throttle valve to be slower than the normal condition.
So, the acceleration will be poor.

EC-388Revision: November 2009
DTC P0447 EVAP CANISTER VENT CONTROL VALVE
2006 QX56
DTC P0447 EVAP CANISTER VENT CONTROL VALVEPFP:14935
Component DescriptionUBS00H4Z
The EVAP canister vent control valve is located on the EVAP canis-
ter and is used to seal the canister vent.
This solenoid valve responds to signals from the ECM. When the
ECM sends an ON signal, the coil in the solenoid valve is energized.
A plunger will then move to seal the canister vent. The ability to seal
the vent is necessary for the on board diagnosis of other evaporative
emission control system components.
This solenoid valve is used only for diagnosis, and usually remains
opened.
When the vent is closed, under normal purge conditions, the evapo-
rative emission control system is depressurized and allows EVAP
Control System diagnosis.
CONSULT-II Reference Value in Data Monitor ModeUBS00H50
Specification data are reference values.
On Board Diagnosis LogicUBS00H51
PBIB1263E
BBIA0443E
MONITOR ITEMCONDITION SPECIFICATION
VENT CONT/V

Ignition switch: ON OFF
DTC No. Trouble diagnosis nameDTC detecting condition Possible cause
P0447
0447 EVAP canister vent con-
trol valve circuit open An improper voltage signal is sent to ECM
through EVAP canister vent control valve.

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

EVAP canister vent control valve

DTC P0448 EVAP CANISTER VENT CONTROL VALVEEC-395
C
DE
F
G H
I
J
K L
M A
EC
Revision: November 2009 2006 QX56
DTC P0448 EVAP CANISTER VENT CONTROL VALVEPFP:16935
Component DescriptionUBS00HB1
The EVAP canister vent control valve is located on the EVAP canis-
ter and is used to seal the canister vent.
This solenoid valve responds to signals from the ECM. When the
ECM sends an ON signal, the coil in the solenoid valve is energized.
A plunger will then move to seal the canister vent. The ability to seal
the vent is necessary for the on board diagnosis of other evaporative
emission control system components.
This solenoid valve is used only for diagnosis, and usually remains
opened.
When the vent is closed, under normal purge conditions, the evapo-
rative emission control system is depressurized and allows EVAP
Control System diagnosis.
CONSULT-II Reference Value in Data Monitor ModeUBS00HB2
Specification data are reference values.
On Board Diagnosis LogicUBS00HB3
PBIB1263E
BBIA0443E
MONITOR ITEMCONDITION SPECIFICATION
VENT CONT/V

Ignition switch: ON OFF
DTC No. Trouble diagnosis nameDTC detecting condition Possible cause
P0448
0448 EVAP canister vent con-
trol valve close EVAP canister vent control valve remains
closed under specified driving conditions.

EVAP canister vent control valve

EVAP control system pressure sensor
and the circuit

Blocked rubber tube to EVAP canister
vent control valve

EVAP canister is saturated with water

DTC P0456 EVAP CONTROL SYSTEMEC-427
C
DE
F
G H
I
J
K L
M A
EC
Revision: November 2009 2006 QX56
DTC P0456 EVAP CONTROL SYSTEMPFP:14950
On Board Diagnosis LogicUBS00H5T
This diagnosis detects very small leaks in the EVAP line between fuel tank and EVAP canister purge volume
control solenoid valve, using the intake manifold vacuum in the same way as conventional EVAP small leak
diagnosis.
If ECM judges a leak which corresponds to a very small leak, the very small leak P0456 will be detected.
If ECM judges a leak equivalent to a small leak, EVAP small leak P0442 will be detected.
If ECM judges there are no leaks, the diagnosis will be OK.
DTC No. Trouble diagnosis name DTC detecting conditionPossible cause
P0456
0456 Evaporative emission
control system very
small leak (negative
pressure check)

EVAP system has a very small leak.

EVAP system does not operate prop-
erly.

Incorrect fuel tank vacuum relief valve

Incorrect fuel filler cap used

Fuel filler cap remains open or fails to close.

Foreign matter caught in fuel filler cap.

Leak is in line between intake manifold and EVAP
canister purge volume control solenoid valve.

Foreign matter caught in EVAP canister vent con-
trol valve.

EVAP canister or fuel tank leaks

EVAP purge line (pipe and rubber tube) leaks

EVAP purge line rubber tube bent

Loose or disconnected rubber tube

EVAP canister vent control valve and the circuit

EVAP canister purge volume control solenoid
valve and the circuit

Fuel tank temperature sensor

O-ring of EVAP canister vent control valve is miss-
ing or damaged

EVAP canister is saturated with water

EVAP control system pressure sensor

Refueling EVAP vapor cut valve

ORVR system leaks

Fuel level sensor and the circuit

Foreign matter caught in EVAP canister purge vol-
ume control solenoid valve
PBIB1026E

EC-470Revision: November 2009
DTC P1148, P1168 CLOSED LOOP CONTROL
2006 QX56
DTC P1148, P1168 CLOSED LOOP CONTROLPFP:22690
On Board Diagnosis LogicUBS00H8K
These self-diagnoses have the one trip detection logic.
DTC P1148 or P1168 is displayed with another DTC for air fuel ratio (A/F) sensor 1.
Perform the trouble diagnosis for the corresponding DTC.
DTC No. Trouble diagnosis nameDTC detecting condition Possible cause
P1148
1148
(Bank 1) Closed loop control
function The closed loop control function for bank 1
does not operate even when vehicle is driving
in the specified condition.

Harness or connectors
[The air fuel ratio (A/F) sensor 1 circuit is
open or shorted.]

Air fuel ratio (A/F) sensor 1

Air fuel ratio (A/F) sensor 1 heater
P1168
1168
(Bank 2) The closed loop control function for bank 2
does not operate even when vehicle is driving
in the specified condition.

DTC P1217 ENGINE OVER TEMPERATUREEC-473
C
DE
F
G H
I
J
K L
M A
EC
Revision: November 2009 2006 QX56
DTC P1217 ENGINE OVER TEMPERATUREPFP:00000
DescriptionUBS00H8T
SYSTEM DESCRIPTION
NOTE:

If DTC P1217 is displayed with DTC U1000 or U1001, first perform the trouble diagnosis for DTC
U1000, U1001. Refer to EC-151, "
DTC U1000, U1001 CAN COMMUNICATION LINE" .

If DTC P1217 is displayed with DTC U1010, first perform the trouble diagnosis for DTC U1010.
Refer to EC-154, "
DTC U1010 CAN COMMUNICATION" .
Cooling Fan Control
*1: The ECM determines the start signal status by the signals of engine speed and battery voltage.
*2: This signal is sent to ECM through CAN communication line.
The ECM controls the cooling fan corresponding to the vehicle speed, engine coolant temperature, refrigerant
pressure, and air conditioner ON signal. The control system has 2-step control [HI/OFF].
Cooling Fan Operation
CONSULT-II Reference Value in Data Monitor ModeUBS00H8U
Specification data are reference values.
Sensor Input signal to ECMECM functionActuator
Crankshaft position sensor (POS)
Camshaft position sensor (PHASE) Engine speed*
1
Cooling fan
controlIPDM E/R
(Cooling fan relay)
Battery
Battery voltage*
1
Wheel sensor*2Vehicle speed
Engine coolant temperature sensor Engine coolant temperature
Air conditioner switch Air conditioner ON signal*
2
Refrigerant pressure sensorRefrigerant pressure
PBIB2060E
MONITOR ITEM CONDITION SPECIFICATION
COOLING FAN

Engine: After warming up, idle
the engine Engine coolant temperature: 99
°C
(210 °F) or less OFF
Engine coolant temperature: 100 °C
(212 °F) or more HI

DTC P1225 TP SENSOREC-483
C
DE
F
G H
I
J
K L
M A
EC
Revision: November 2009 2006 QX56
DTC P1225 TP SENSORPFP:16119
Component DescriptionUBS00H91
Electric throttle control actuator consists of throttle control motor,
throttle position sensor, etc. The throttle position sensor responds to
the throttle valve movement.
The throttle position sensor has the two sensors. These sensors are
a kind of potentiometers which transform the throttle valve position
into output voltage, and emit the voltage signal to the ECM. In addi-
tion, these sensors detect the opening and closing speed of the
throttle valve and feed the voltage signals to the ECM. The ECM
judges the current opening angle of the throttle valve from these sig-
nals and the ECM controls the throttle control motor to make the
throttle valve opening angle properly in response to driving condi-
tion.
On Board Diagnosis LogicUBS00H92
The MIL will not light up for this diagnosis.
DTC Confirmation ProcedureUBS00H93
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.
TESTING CONDITION:
Before performing the following procedure, confirm that battery voltage is more than 10V at idle.
WITH CONSULT-II
1. Turn ignition switch ON.
2. Select “DATA MONITOR ” mode with CONSULT-II.
3. Turn ignition switch OFF and wait at least 10 seconds.
4. Turn ignition switch ON.
5. If 1st trip DTC is detected, go to EC-484, "
Diagnostic Procedure"
.
WITH GST
Follow the procedure “WITH CONSULT-II” above.
PBIB0145E
DTC No. Trouble diagnosis name DTC detecting conditionPossible cause
P1225
1225 Closed throttle position learning
performance Closed throttle position learning value is
excessively low.

Electric throttle control actuator
(TP sensor 1 and 2)
SEF058Y