Ins INFINITI QX56 2004 Factory Service Manual

DTC P0138, P0158 HO2S2
EC-195
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Revision: August 20072004 QX56
6. Check the voltage when revving up to 4,000 rpm under no load
at least 10 times.
(Depress and release accelerator pedal as soon as possible.)
The voltage should be above 0.70V at least once during this
procedure.
If the voltage is above 0.70V at step 6, step 7 is not neces-
sary.
7. Keep vehicle at idling for 10 minutes, then check voltage. Or
check the voltage when coasting from 80 km/h (50 MPH) in D
position.
The voltage should be below 0.18V at least once during this
procedure.
8. If NG, replace heated oxygen sensor 2.
CAUTION:

Discard any heated oxygen sensor which has been dropped from a height of more than 0.5 m (19.7
in) onto a hard surface such as a concrete floor; use a new one.

Before installing new oxygen sensor, clean exhaust system threads (using Oxygen Sensor Thread
Cleaner tool J-43897-18 or J-43897-12) and approved anti-seize lubricant.
Removal and InstallationUBS00H2M
HEATED OXYGEN SENSOR 2
Refer to EM-19, "EXHAUST MANIFOLD AND THREE WAY CATALYST" .
PBIB2054E

DTC P0139, P0159 HO2S2
EC-197
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Revision: August 20072004 QX56
DTC Confirmation ProcedureUBS00H2Q
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
TESTING CONDITION:
For better results, perform “DTC WORK SUPPORT” at a temperature of 0 to 30 °C (32 to 86 °F).
1. Turn ignition switch ON and select “DATA MONITOR” mode with
CONSULT-II.
2. Start engine and warm it up to the normal operating tempera-
ture.
3. Turn ignition switch OFF and wait at least 10 seconds.
4. Start engine and keep the engine speed between 3,500 and
4,000 rpm for at least 1 minute under no load.
5. Let engine idle for 1 minute.
6. Make sure that “COOLAN TEMP/S” indicates more than 70°C
(158°F).
If not, warm up engine and go to next step when “COOLAN
TEMP/S” indication reaches to 70°C (158°F).
7. Select “HO2S2 (B1) P0139” or “HO2S2 (B2) P0159” of “HO2S2” in “DTC WORK SUPPORT” mode with
CONSULT-II.
8. Start engine and following the instruction of CONSULT-II.
9. Make sure that “OK” is displayed after touching “SELF-DIAG RESULTS”.
If “NG” is displayed, refer to EC-202, "
Diagnostic Procedure" .
If “CAN NOT BE DIAGNOSED” is displayed, perform the following.
a. Turn ignition switch OFF and leave the vehicle in a cool place (soak the vehicle).
b. Return to step 1.
Overall Function CheckUBS00H2R
Use this procedure to check the overall function of the heated oxygen sensor 2 circuit. During this check, a 1st
trip DTC might not be confirmed.
WITH GST
1. Start engine and warm it up to the normal operating temperature.
2. Turn ignition switch OFF and wait at least 10 seconds.
3. Start engine and keep the engine speed between 3,500 and 4,000 rpm for at least 1 minute under no load.
4. Let engine idle for 1 minute.
5. Set voltmeter probes between ECM terminal 55 [HO2S2 (B1) signal] or 74 [HO2S2 (B2) signal] and
ground.
SEF 1 74 Y
PBIB0115E

EC-202Revision: August 2007
DTC P0139, P0159 HO2S2
2004 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 ProcedureUBS00H2T
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
COLORITEM CONDITION DATA (DC Voltage)
74 LHeated oxygen sensor 2
(bank 2)[Engine is running]

Warm-up condition

Revving engine from idle to 3,000 rpm
quickly after the following conditions are met
–After keeping the engine speed between
3,500 and 4,000 rpm for 1 minute and at idle
for 1 minute under no load0 - Approximately 1.0V
BBIA0354E

DTC P0139, P0159 HO2S2
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Revision: August 20072004 QX56
5. CHECK HO2S2 INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT
1. Disconnect ECM harness connector.
2. Check harness continuity between ECM terminal and HO2S2 terminal as follows.
Refer to Wiring Diagram.
3. Check harness continuity between the following terminals and ground.
Refer to Wiring Diagram.
4. Also check harness for short to ground and short to power.
OK or NG
OK >> GO TO 6.
NG >> Repair open circuit or short to ground or short to power in harness or connectors.
6. CHECK HEATED OXYGEN SENSOR 2
Refer to EC-205, "
Component Inspection" .
OK or NG
OK >> GO TO 7.
NG >> Replace malfunctioning heated oxygen sensor 2.
7. CHECK INTERMITTENT INCIDENT
Refer to EC-127, "
TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT" .
>>INSPECTION END
Component InspectionUBS00H2U
HEATED OXYGEN SENSOR 2
With CONSULT-II
1. Turn ignition switch ON and select “DATA MONITOR” mode with
CONSULT-II.
2. Start engine and warm it up to the normal operating tempera-
ture.
3. Turn ignition switch OFF and wait at least 10 seconds.
4. Start engine and keep the engine speed between 3,500 and
4,000 rpm for at least 1 minute under no load.
5. Let engine idle for 1 minute.
DTCTe r m i n a l s
Bank
ECM Sensor
P0139 55 1 1
P0159 74 1 2
Continuity should exist.
DTCTe r m i n a l s
Bank
ECM Sensor
P0139 55 1 1
P0159 74 1 2
Continuity should not exist.
SEF 1 74 Y

EC-206Revision: August 2007
DTC P0139, P0159 HO2S2
2004 QX56
6. Select “FUEL INJECTION” in “ACTIVE TEST” mode, and select
“HO2S2 (B1)/(B2)” as the monitor item with CONSULT-II.
7. Check “HO2S2 (B1)/(B2)” at idle speed when adjusting “FUEL INJECTION” to ±25%.
“HO2S2 (B1)/(B2)” should be above 0.70V at least once when the “FUEL INJECTION” is +25%.
“HO2S2 (B1)/(B2)” should be below 018V at least once when the “FUEL INJECTION” is −25%.
CAUTION:

Discard any heated oxygen sensor which has been dropped from a height of more than 0.5 m (19.7
in) onto a hard surface such as a concrete floor; use a new one.

Before installing new oxygen sensor, clean exhaust system threads using Oxygen Sensor Thread
Cleaner tool J-43897-18 or J-43897-12 and approved anti-seize lubricant.
Without CONSULT-II
1. Start engine and warm it up to the normal operating temperature.
2. Turn ignition switch OFF and wait at least 10 seconds.
3. Start engine and keep the engine speed between 3,500 and 4,000 rpm for at least 1 minute under no load.
4. Let engine idle for 1 minute.
5. Set voltmeter probes between ECM terminal 55 [HO2S2 (B1) signal] or 74 [HO2S2 (B2) signal] and
ground.
6. Check the voltage when revving up to 4,000 rpm under no load
at least 10 times.
(Depress and release accelerator pedal as soon as possible.)
The voltage should be above 0.70V at least once during this
procedure.
If the voltage is above 0.70V at step 6, step 7 is not neces-
sary.
7. Keep vehicle at idling for 10 minutes, then check voltage. Or
check the voltage when coasting from 80 km/h (50 MPH) in D
position.
The voltage should be below 0.18V at least once during this
procedure.
8. If NG, replace heated oxygen sensor 2.
CAUTION:

Discard any heated oxygen sensor which has been dropped from a height of more than 0.5 m (19.7
in) onto a hard surface such as a concrete floor; use a new one.

Before installing new oxygen sensor, clean exhaust system threads using Oxygen Sensor Thread
Cleaner tool J-43897-18 or J-43897-12 and approved anti-seize lubricant.
PBIB1672E
PBIB1210E
PBIB2054E

DTC P0139, P0159 HO2S2
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Revision: August 20072004 QX56
Removal and InstallationUBS00H2V
HEATED OXYGEN SENSOR 2
Refer to EM-19, "EXHAUST MANIFOLD AND THREE WAY CATALYST" .

EC-214Revision: August 2007
DTC P0171, P0174 FUEL INJECTION SYSTEM FUNCTION
2004 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" .)

Fuel lines

Fuel filter for clogging
>> 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-216Revision: August 2007
DTC P0171, P0174 FUEL INJECTION SYSTEM FUNCTION
2004 QX56
9. CHECK INTERMITTENT INCIDENT
Refer to EC-127, "
TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT" .
>>INSPECTION END

DTC P0172, P0175 FUEL INJECTION SYSTEM FUNCTION
EC-223
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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