2009 INFINITI QX56 200

P0448 EVAP CANISTER VENT CONTROL VALVEEC-237
< COMPONENT DIAGNOSIS > [VK56DE]
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OOperation takes less than 1 second.
If NG, replace EVAP canister vent control valve.
If OK, go to next step.
7. Clean the air passage (Portion A to B) of EVAP canister vent control valve using an air blower.
8. Perform step 6 again.
Without CONSULT-III
1. Remove EVAP canister vent c ontrol valve from EVAP canister.
2. Check portion B of EVAP canister vent control valve for being
rusted.
3. Check air passage continuity and operation delay time under the following conditions.
Make sure that new O-ring is installed properly.
Operation takes less than 1 second.
If NG, replace EVAP canister vent control valve.
If OK, go to next step.
4. Clean the air passage (Portion A to B) of EVAP canister vent control valve using an air blower.
5. Perform step 3 again.
Condition VENT CONTROL/V Air passage continuity between A and B
ON No
OFF Yes
PBIB1033E
Condition Air passage continuity between A and B
12V direct current supply between
terminals 1 and 2 No
OFF Yes
PBIB1034E
Revision: December 20092009 QX56

EC-238
< COMPONENT DIAGNOSIS >[VK56DE]
P0451 EVAP CONTROL S
YSTEM PRESSURE SENSOR
P0451 EVAP CONTROL SYSTEM PRESSURE SENSOR
Component DescriptionINFOID:0000000003771505
The EVAP control system pressure sens or detects pressure in the purge line. The sensor output voltage to the
ECM increases as pressure increases.
On Board Diagn osis LogicINFOID:0000000003771506
NOTE:
If DTC P0451 is displayed with DTC P0643, first pe rform the trouble diagnosis for DTC P0643. Refer to
EC-285
.
DTC Confirmation ProcedureINFOID:0000000003771507
1. If DTC Confirmation Procedure has been previously conducted, always perform the following before con-
ducting the next step.
a. Turn ignition switch OFF and wait at least 10 seconds.
b. Turn ignition switch ON.
c. Turn ignition switch OFF and wait at least 10 seconds.
2. Start engine and wait at least 40 seconds. NOTE:
Do not depress accelerator pedal even slightly.
3. Check 1st trip DTC.
4. If 1st trip DTC is detected, go to EC-238, "Diagnosis Procedure"
.
Diagnosis ProcedureINFOID:0000000003771508
1.CHECK GROUND CONNECTIONS
1. Turn ignition switch OFF.
2. Loosen and retighten three ground screws on the body.
BBIA0443E
PBIB1207E
DTC No. Trouble diagnosis name DTC detecting condition Possible cause
P0451
0451 EVAP control system pressure
sensor performance ECM detects a sloshing signal from the
EVAP control system pressure sensor  Harness or connectors
 EVAP control system pressure sensor
Revision: December 20092009 QX56

P0451 EVAP CONTROL SYSTEM PRESSURE SENSOREC-239
< COMPONENT DIAGNOSIS > [VK56DE]
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Refer to
EC-85, "Ground Inspection".
OK or NG
OK >> GO TO 2.
NG >> Repair or replace ground connections.
2.CHECK EVAP CONTROL SYS TEM PRESSURE SENSOR CONNECTOR FOR WATER
1. Disconnect EVAP control system pressure sensor harness connector.
2. Check sensor harness connector for water.
OK or NG
OK >> GO TO 3.
NG >> Repair or replace harness connector.
3.CHECK EVAP CONTROL SYS TEM PRESSURE SENSOR
Refer to EC-239, "Component Inspection"
.
OK or NG
OK >> GO TO 4.
NG >> Replace EVAP control system pressure sensor.
4.CHECK INTERMITTENT INCIDENT
Refer to GI-35, "How to Check Terminal"
and GI-38, "Intermittent Incident".
For wiring diagram, refer to EC-242, "Diagnosis Procedure"
.
>> INSPECTION END
Component InspectionINFOID:0000000003771509
EVAP CONTROL SYSTEM PRESSURE SENSOR
1. Remove EVAP control system pr essure sensor with its harness connec tor connected from EVAP canister.
Always replace O-ring with a new one.
2. Install a vacuum pump to EVAP control system pressure sensor.
BBIA0354E
Water should not exist.
BBIA0443E
Revision: December 20092009 QX56

EC-240
< COMPONENT DIAGNOSIS >[VK56DE]
P0451 EVAP CONTROL S
YSTEM PRESSURE SENSOR
3. Turn ignition switch ON and check output voltage between ECM
terminal 32 and ground under the following conditions.
CAUTION:
 Always calibrate the vacuum pump gauge when using it.
 Do not apply below -93.3 kP a (-700 mmHg, -27.56 inHg) or
pressure over 101.3 kPa (760 mmHg, 29.92 inHg).
4. If NG, replace EVAP control system pressure sensor.
Applied vacuum kPa (mmHg, inHg) Voltage V
Not applied 1.8 - 4.8
-26.7 (-200, -7.87) 2.1 to 2.5V lower than above value
PBIB1173E
Revision: December 20092009 QX56

P0452 EVAP CONTROL SYSTEM PRESSURE SENSOREC-241
< COMPONENT DIAGNOSIS > [VK56DE]
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P0452 EVAP CONTROL SYSTEM
PRESSURE SENSOR
Component DescriptionINFOID:0000000003771510
The EVAP control system pressure sens or detects pressure in the purge line. The sensor output voltage to the
ECM increases as pressure increases.
On Board Diagnosis LogicINFOID:0000000003771511
NOTE:
If DTC P0452 is displayed with DTC P0643, first pe rform the trouble diagnosis for DTC P0643. Refer to
EC-285
.
DTC Confirmation ProcedureINFOID:0000000003771512
NOTE:
If DTC Confirmation Procedure has been previously conduc ted, always perform the following before conduct-
ing the next step.
1. Turn ignition swich OFF and wait at least 10 seconds.
2. Turn ignition swich ON.
3. Turn ignition swich OFF and wait at least 10 seconds.
TESTING CONDITION:
Always perform test at a temperature of 5 °C (41 °F) or more.
WITH CONSULT-III
1. Start engine and warm it up to normal operating temperature.
2. Turn ignition switch OFF and wait at least 10 seconds.
3. Turn ignition switch ON.
4. Select “DATA MONITOR” mode with CONSULT-III.
5. Make sure that “FUEL T/TMP SE” is more than 0 °C (32 °F).
BBIA0443E
PBIB1207E
DTC No. Trouble diagnosis name DTC detecting condition Possible cause
P0452
0452 EVAP control system pressure
sensor low input An excessively low voltage from the sen-
sor is sent to ECM.  Harness or connectors
(The sensor circuit is open or shorted.)
 EVAP control system pressure sensor
Revision: December 20092009 QX56

EC-242
< COMPONENT DIAGNOSIS >[VK56DE]
P0452 EVAP CONTROL S
YSTEM PRESSURE SENSOR
6. Start engine and wait at least 20 seconds.
7. Check 1st trip DTC.
8. If 1st trip DTC is detected, go to EC-242, "Diagnosis Procedure"
.
WITH GST
1. Start engine and warm it up to normal operating temperature.
2. Check that voltage between ECM terminal 107 (Fuel tank tem-
perature sensor signal) and ground is less than 4.2V.
3. Turn ignition switch OFF and wait at least 10 seconds.
4. Start engine and wait at least 20 seconds.
5. Select Service $07 with GST. If 1st trip DTC is detected, go to EC-242, "Diagnosis Procedure"
.
Diagnosis ProcedureINFOID:0000000003771513
1.CHECK GROUND CONNECTIONS
1. Turn ignition switch OFF.
2. Loosen and retighten three ground screws on the body. Refer to EC-85, "Ground Inspection"
.
OK or NG
OK >> GO TO 2.
NG >> Repair or replace ground connections.
2.CHECK CONNECTOR
1. Disconnect EVAP control system pressure sensor harness connector.
2. Check sensor harness connector for water.
OK or NG
OK >> GO TO 3.
NG >> Repair or replace harness connector.
PBIB1110E
BBIA0354E
Water should not exist.
BBIA0443E
Revision: December 20092009 QX56

P0452 EVAP CONTROL SYSTEM PRESSURE SENSOREC-243
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3.CHECK EVAP CONTROL SYS
TEM PRESSURE SENSOR POWER SUPPLY CIRCUIT
1. Turn ignition switch ON.
2. Check voltage between EVAP control system pressure sensor terminal 3 and ground with CONSULT-III or tester.
OK or NG
OK >> GO TO 5.
NG >> GO TO 4.
4.DETECT MALFUNCTIONING PART
Check the following.
 Harness connectors C1, E41
 Harness connectors E5, F14
 Harness for open or short between EVAP c ontrol system pressure sensor and ECM
>> Repair open circuit or short to ground or short to power in harness or connectors.
5.CHECK EVAP CONTROL SYSTEM PRESSURE SENSOR GROUND CIRCUIT FOR OPEN AND SHORT
1. Turn ignition switch OFF.
2. Disconnect ECM harness connector.
3. Check harness continuity between EVAP control s ystem pressure sensor terminal 1 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 7.
NG >> GO TO 6.
6.DETECT MALFUNCTIONING PART
Check the following.
 Harness connectors C1, E41
 Harness connectors E5, F14
 Harness for open or short between EVAP c ontrol system pressure sensor and ECM
>> Repair open circuit or short to ground or short to power in harness or connectors.
7.CHECK EVAP CONTROL SYSTEM PRESSURE SENS OR INPUT SIGNAL CIRCUIT FOR OPEN AND
SHORT
1. Check harness continuity between ECM terminal 32 and EVAP control system pressure sensor terminal 2.
Refer to Wiring Diagram.
2. Also check harness for short to ground and short to power.
OK or NG
OK >> GO TO 9.
NG >> GO TO 8.
8.DETECT MALFUNCTIONING PART Voltage: Approximately 5V
PBIB0138E
Continuity should exist.
Continuity should exist.
Revision: December 20092009 QX56

EC-244
< COMPONENT DIAGNOSIS >[VK56DE]
P0452 EVAP CONTROL S
YSTEM PRESSURE SENSOR
Check the following.
 Harness connectors C1, E41
 Harness connectors E5, F14
 Harness for open or short between EVAP control system pressure sensor and ECM
>> Repair open circuit or short to ground or short to power in harness or connectors.
9.CHECK EVAP CONTROL SY STEM PRESSURE SENSOR
Refer to EC-244, "Component Inspection"
.
OK or NG
OK >> GO TO 10.
NG >> Replace EVAP control system pressure sensor.
10.CHECK INTERMITTENT INCIDENT
Refer to GI-35, "How to Check Terminal"
and GI-38, "Intermittent Incident".
>> INSPECTION END
Component InspectionINFOID:0000000003771514
EVAP CONTROL SYSTEM PRESSURE SENSOR
1. Remove EVAP control system pressure sensor wit h its harness connector connected from EVAP canister.
Always replace O-ring with a new one.
2. Install a vacuum pump to EVAP control system pressure sensor.
3. Turn ignition switch ON and check output voltage between ECM terminal 32 and ground under the following conditions.
CAUTION:
 Always calibrate the vacuum pump gauge when using it.
 Do not apply below -93.3 kP a (-700 mmHg, -27.56 inHg) or
pressure over 101.3 kPa (760 mmHg, 29.92 inHg).
4. If NG, replace EVAP control system pressure sensor.
Applied vacuum [kPa (mmHg, inHg)] Voltage (V)
Not applied 1.8 - 4.8
-26.7 (-200, -7.87) 2.1 to 2.5 lower than above value
PBIB1173E
Revision: December 20092009 QX56