2004 INFINITI QX56 engine

EC-48Revision: August 2007
BASIC SERVICE PROCEDURE
2004 QX56
4. Install Fuel Pressure Adapter J-44321-6 and Fuel Pressure
Gauge (from kit J-44321) as shown in figure.

Do not distort or bend fuel rail tube when installing fuel pres-
sure gauge adapter.

When reconnecting fuel hose, check the original fuel hose for
damage and abnormality.
5. Turn ignition switch ON (reactivate fuel pump), and check for
fuel leakage.
6. Start engine and check for fuel leakage.
7. Read the indication of fuel pressure gauge.

During fuel pressure check, check for fuel leakage from fuel
connection every 3 minutes.
8. If result is unsatisfactory, go to next step.
9. Check the following.

Fuel hoses and fuel tubes for clogging

Fuel filter for clogging

Fuel pump

Fuel pressure regulator for clogging
If OK, replace fuel pressure regulator.
If NG, repair or replace.
10. Before disconnecting Fuel Pressure Gauge and Fuel Pressure Adapter J-44321-6, release fuel pressure
to zero. Refer to EC-46, "
FUEL PRESSURE RELEASE" . At idling:
Approximately 350 kPa (3.57 kg/cm
2 , 51 psi)
BBIA0390E

ON BOARD DIAGNOSTIC (OBD) SYSTEM
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Revision: August 20072004 QX56
ON BOARD DIAGNOSTIC (OBD) SYSTEMPFP:00028
IntroductionUBS00GZQ
The ECM has an on board diagnostic system, which detects malfunctions related to engine sensors or actua-
tors. The ECM also records various emission-related diagnostic information including:
The above information can be checked using procedures listed in the table below.
×: Applicable —: Not applicable
*: When DTC and 1st trip DTC simultaneously appear on the display, they cannot be clearly distinguished from each other.
The malfunction indicator lamp (MIL) on the instrument panel lights up when the same malfunction is detected
in two consecutive trips (Two trip detection logic), or when the ECM enters fail-safe mode. (Refer to EC-77,
"Fail-safe Chart" .)
Two Trip Detection LogicUBS00GZR
When a malfunction is detected for the first time, 1st trip DTC and 1st trip Freeze Frame data are stored in the
ECM memory. The MIL will not light up at this stage. <1st trip>
If the same malfunction is detected again during the next drive, the DTC and Freeze Frame data are stored in
the ECM memory, and the MIL lights up. The MIL lights up at the same time when the DTC is stored. <2nd
trip> The “trip” in the “Two Trip Detection Logic” means a driving mode in which self-diagnosis is performed
during vehicle operation. Specific on board diagnostic items will cause the ECM to light up or blink the MIL,
and store DTC and Freeze Frame data, even in the 1st trip, as shown below.
×: Applicable —: Not applicable
When there is an open circuit on MIL circuit, the ECM cannot warn the driver by lighting MIL up when there is
malfunction on engine control system.
Therefore, when electrical controlled throttle and part of ECM related diagnoses are continuously detected as
NG for 5 trips, ECM warns the driver that engine control system malfunctions and MIL circuit is open by means
of operating fail-safe function.
Emission-related diagnostic information SAE Mode
Diagnostic Trouble Code (DTC) Mode 3 of SAE J1979
Freeze Frame data Mode 2 of SAE J1979
System Readiness Test (SRT) code Mode 1 of SAE J1979
1st Trip Diagnostic Trouble Code (1st Trip DTC) Mode 7 of SAE J1979
1st Trip Freeze Frame data
Test values and Test limits Mode 6 of SAE J1979
Calibration ID Mode 9 of SAE J1979
DTC 1st trip DTCFreeze Frame
data1st trip Freeze
Frame dataSRT code Test value
CONSULT-II×× × × ×—
GST×× ×—××
ECM××*— ———
ItemsMIL DTC 1st trip DTC
1st trip 2nd trip
1st trip
displaying2nd trip
displaying1st trip
displaying2nd trip
display-
ing BlinkingLighting
upBlinkingLighting
up
Misfire (Possible three way catalyst
damage) — DTC: P0300 - P0308 is
being detected×———— —×—
Misfire (Possible three way catalyst
damage) — DTC: P0300 - P0308 is
being detected——×——×——
One trip detection diagnoses (Refer
to EC-8, "
INDEX FOR DTC" .)—×——×———
Except above — — —×—××—

EC-50Revision: August 2007
ON BOARD DIAGNOSTIC (OBD) SYSTEM
2004 QX56
The fail-safe function also operates when above diagnoses except MIL circuit are detected, and demands the
driver to repair the malfunction.
Emission-related Diagnostic InformationUBS00GZS
EMISSION-RELATED DIAGNOSTIC INFORMATION ITEMS
×: Applicable —: Not applicable Engine operating condition in fail-safe mode Engine speed will not rise more than 2,500 rpm due to the fuel cut
Items
(CONSULT-II screen terms)DTC*
1
SRT codeTest value/
Test limit
(GST only)1st trip DTCReference
page CONSULT-II
GST*
2ECM*3
CAN COMM CIRCUIT U1000
1000*5———EC-135
CAN COMM CIRCUIT U1001
1001*5——×EC-135
NO DTC IS DETECTED.
FURTHER TESTING
MAY BE REQUIRED.P0000 0000————
HO2S2 HTR (B1) P0037 0037×××EC-138
HO2S2 HTR (B1) P0038 0038×××EC-138
HO2S2 HTR (B2) P0057 0057×××EC-138
HO2S2 HTR (B2) P0058 0058×××EC-138
MAF SEN/CIRCUIT P0101 0101 — — —EC-146
MAF SEN/CIRCUIT P0102 0102 — — —EC-154
MAF SEN/CIRCUIT P0103 0103 — — —EC-154
IAT SEN/CIRCUIT P0112 0112 — —×EC-161
IAT SEN/CIRCUIT P0113 0113 — —×EC-161
ECT SEN/CIRCUIT P0117 0117 — — —EC-165
ECT SEN/CIRCUIT P0118 0118 — — —EC-165
TP SEN 2/CIRC P0122 0122 — — —EC-171
TP SEN 2/CIRC P0123 0123 — — —EC-171
ECT SENSOR P0125 0125 — — —EC-178
IAT SENSOR P0127 0127 — —×EC-181
THERMSTAT FNCTN P0128 0128 — —×EC-184
HO2S2 (B1) P0138 0138 —××EC-186
HO2S2 (B1) P0139 0139×××EC-196
HO2S2 (B2) P0158 0158 —××EC-186
HO2S2 (B2) P0159 0159×××EC-196
FUEL SYS-LEAN-B1 P0171 0171 — —×EC-208
FUEL SYS-RICH-B1 P0172 0172 — —×EC-217
FUEL SYS-LEAN-B2 P0174 0174 — —×EC-208
FUEL SYS-RICH-B2 P0175 0175 — —×EC-217
FTT SENSOR P0181 0181 — —×EC-225
FTT SEN/CIRCUIT P0182 0182 — —×EC-231
FTT SEN/CIRCUIT P0183 0183 — —×EC-231
TP SEN 1/CIRC P0222 0222 — — —EC-236
TP SEN 1/CIRC P0223 0223 — — —EC-236
MULTI CYL MISFIRE P0300 0300 — —×EC-243
CYL 1 MISFIRE P0301 0301 — —×EC-243
CYL 2 MISFIRE P0302 0302 — —×EC-243

EC-54Revision: August 2007
ON BOARD DIAGNOSTIC (OBD) SYSTEM
2004 QX56
1st trip DTC is specified in Mode 7 of SAE J1979. 1st trip DTC detection occurs without lighting up the MIL and
therefore does not warn the driver of a malfunction. However, 1st trip DTC detection will not prevent the vehi-
cle from being tested, for example during Inspection/Maintenance (I/M) tests.
When a 1st trip DTC is detected, check, print out or write down and erase (1st trip) DTC and Freeze Frame
data as specified in Work Flow procedure Step II, refer to EC-72, "
WORK FLOW" . Then perform DTC Confir-
mation Procedure or Overall Function Check to try to duplicate the malfunction. If the malfunction is dupli-
cated, the item requires repair.
How to Read DTC and 1st Trip DTC
DTC and 1st trip DTC can be read by the following methods.
With CONSULT-II
With GST
CONSULT-II or GST (Generic Scan Tool) Examples: P0340, P1148, P1706, etc.
These DTCs are prescribed by SAE J2012.
(CONSULT-II also displays the malfunctioning component or system.)
No Tools
The number of blinks of the MIL in the Diagnostic Test Mode II (Self-Diagnostic Results) indicates the DTC.
Example: 0340, 1148, 1706, etc.
These DTCs are controlled by NISSAN.

1st trip DTC No. is the same as DTC No.

Output of a DTC indicates a malfunction. However, GST or the Diagnostic Test Mode II do not indi-
cate whether the malfunction is still occurring or has occurred in the past and has returned to nor-
mal. CONSULT-II can identify malfunction status as shown below. Therefore, using CONSULT-II (if
available) is recommended.
A sample of CONSULT-II display for DTC and 1st trip DTC is shown below. DTC or 1st trip DTC of a malfunc-
tion is displayed in “SELF-DIAGNOSTIC RESULTS” mode of CONSULT-II. Time data indicates how many
times the vehicle was driven after the last detection of a DTC.
If the DTC is being detected currently, the time data will be [0].
If a 1st trip DTC is stored in the ECM, the time data will be [1t].
FREEZE FRAME DATA AND 1ST TRIP FREEZE FRAME DATA
The ECM records the driving conditions such as fuel system status, calculated load value, engine coolant tem-
perature, short term fuel trim, long term fuel trim, engine speed, vehicle speed, base fuel schedule and intake
air temperature at the moment a malfunction is detected.
Data which are stored in the ECM memory, along with the 1st trip DTC, are called 1st trip freeze frame data.
The data, stored together with the DTC data, are called freeze frame data and displayed on CONSULT-II or
GST. The 1st trip freeze frame data can only be displayed on the CONSULT-II screen, not on the GST. For
details, see EC-107, "
Freeze Frame Data and 1st Trip Freeze Frame Data" .
Only one set of freeze frame data (either 1st trip freeze frame data or freeze frame data) can be stored in the
ECM. 1st trip freeze frame data is stored in the ECM memory along with the 1st trip DTC. There is no priority
for 1st trip freeze frame data and it is updated each time a different 1st trip DTC is detected. However, once
freeze frame data (2nd trip detection/MIL on) is stored in the ECM memory, 1st trip freeze frame data is no
longer stored. Remember, only one set of freeze frame data can be stored in the ECM. The ECM has the fol-
lowing priorities to update the data.
PBIB09 11 E

EC-60Revision: August 2007
ON BOARD DIAGNOSTIC (OBD) SYSTEM
2004 QX56

The time required for each diagnosis varies with road surface conditions, weather, altitude, individual driv-
ing habits, etc.
Zone A refers to the range where the time, required for the diagnosis under normal conditions*, is the
shortest.
Zone B refers to the range where the diagnosis can still be performed if the diagnosis is not completed
within zone A.
*: Normal conditions refer to the following:

Sea level

Flat road

Ambient air temperature: 20 - 30°C (68 - 86°F)

Diagnosis is performed as quickly as possible under normal conditions.
Under different conditions [For example: ambient air temperature other than 20 - 30°C (68 - 86°F)], diag-
nosis may also be performed.
Pattern 1:

The engine is started at the engine coolant temperature of −10 to 35°C (14 to 95°F)
(where the voltage between the ECM terminal 73 and ground is 3.0 - 4.3V).

The engine must be operated at idle speed until the engine coolant temperature is greater than
70°C (158°F) (where the voltage between the ECM terminal 73 and ground is lower than 1.4V).

The engine is started at the fuel tank temperature of warmer than 0°C (32°F) (where the voltage
between the ECM terminal 107 and ground is less than 4.1V).
Pattern 2:

When steady-state driving is performed again even after it is interrupted, each diagnosis can be con-
ducted. In this case, the time required for diagnosis may be extended.
Pattern 3:

Operate vehicle following the driving pattern shown in the figure.

Release the accelerator pedal during decelerating vehicle speed
from 90 km/h (56 MPH) to 0 km/h (0 MPH).
Pattern 4:

The accelerator pedal must be held very steady during steady-
state driving.

If the accelerator pedal is moved, the test must be conducted all
over again.
*1: Depress the accelerator pedal until vehicle speed is 90 km/h (56
MPH), then release the accelerator pedal and keep it released for
more than 10 seconds. Depress the accelerator pedal until vehicle
speed is 90 km/h (56 MPH) again.
*2: Checking the vehicle speed with GST is advised.
Suggested Transmission Gear Position
Set the selector lever in the D position.
TEST VALUE AND TEST LIMIT (GST ONLY — NOT APPLICABLE TO CONSULT-II)
The following is the information specified in Mode 6 of SAE J1979.
The test value is a parameter used to determine whether a system/circuit diagnostic test is OK or NG while
being monitored by the ECM during self-diagnosis. The test limit is a reference value which is specified as the
maximum or minimum value and is compared with the test value being monitored.
These data (test value and test limit) are specified by Test ID (TID) and Component ID (CID) and can be dis-
played on the GST screen.
PBIB2244E
SRT item Self-diagnostic test item DTCTest value (GST display)
Test limit Conversion
TID CID
CATALYSTThree way catalyst function (Bank 1)P0420 01H 01H Max. 1/128
P0420 02H 81H Min. 1
Three way catalyst function (Bank 2)P0430 03H 02H Max. 1/128
P0430 04H 82H Min. 1

EC-62Revision: August 2007
ON BOARD DIAGNOSTIC (OBD) SYSTEM
2004 QX56
HOW TO ERASE EMISSION-RELATED DIAGNOSTIC INFORMATION
How to Erase DTC
With CONSULT-II
The emission related diagnostic information in the ECM can be erased by selecting “ERASE” in the “SELF-
DIAG RESULTS” mode with CONSULT-II.
If DTCs are displayed for both ECM and TCM (Transmission control module), they need to be erased individu-
ally from the ECM and TCM (Transmission control module).
NOTE:
If the DTC is not for A/T related items (see EC-8
), skip steps 2 through 4.
1. If the ignition switch stays ON after repair work, be sure to turn ignition switch OFF once. Wait at least 10
seconds and then turn it ON (engine stopped) again.
2. Turn CONSULT-II ON and touch “A/T”.
3. Touch “SELF-DIAG RESULTS”.
4. Touch “ERASE”. [The DTC in the TCM (Transmission control module) will be erased.] Then touch “BACK”
twice.
5. Touch “ENGINE”.
6. Touch “SELF-DIAG RESULTS”.
7. Touch “ERASE”. (The DTC in the ECM will be erased.)
With GST
The emission related diagnostic information in the ECM can be erased by selecting MODE 4 with GST.
NOTE:
If the DTC is not for A/T related items (see EC-8
), skip step 2.
1. If the ignition switch stays ON after repair work, be sure to turn ignition switch OFF once. Wait at least 10
seconds and then turn it ON (engine stopped) again.
SCIA5334E

ON BOARD DIAGNOSTIC (OBD) SYSTEM
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Revision: August 20072004 QX56
2. Perform AT-41, "HOW TO ERASE DTC (WITH GST)" . (The DTC in the TCM will be erased.)
3. Select MODE 4 with GST. (The DTC in the ECM will be erased.)
No Tools
NOTE:
If the DTC is not for A/T related items (see EC-8
), skip step 3.
1. If the ignition switch stays ON after repair work, be sure to turn ignition switch OFF once.
2. Wait at least 10 seconds and then turn it ON (engine stopped) again.
3. Perform AT-41, "
HOW TO ERASE DTC (NO TOOLS)" . (The DTC in the TCM will be erased.)
4. Change the diagnostic test mode from Mode II to Mode I by depressing the accelerator pedal. Refer to
EC-64, "
HOW TO SWITCH DIAGNOSTIC TEST MODE" .

If the battery is disconnected, the emission-related diagnostic information will be lost within 24
hours.

The following data are cleared when the ECM memory is erased.
–Diagnostic trouble codes
–1st trip diagnostic trouble codes
–Freeze frame data
–1st trip freeze frame data
–System readiness test (SRT) codes
–Test values
–Others
Actual work procedures are explained using a DTC as an example. Be careful so that not only the DTC, but all
of the data listed above, are cleared from the ECM memory during work procedures.
IVIS (Infiniti Vehicle Immobilizer System — NATS)UBS00GZT

If the security indicator lights up with the ignition switch in
the ON position or “NATS MALFUNCTION” is displayed on
“SELF-DIAG RESULTS” screen, perform self-diagnostic
results mode with CONSULT-II using NATS program card.
Refer to BL-138, "
IVIS (INFINITI VEHICLE IMMOBILIZER
SYSTEM-NATS)" .

Confirm no self-diagnostic results of IVIS (NATS) is dis-
played before touching “ERASE” in “SELF-DIAG RESULTS”
mode with CONSULT-II.

When replacing ECM, initialization of IVIS (NATS) system
and registration of all IVIS (NATS) ignition key IDs must be
carried out with CONSULT-II using NATS program card.
Therefore, be sure to receive all keys from vehicle owner. Regarding the procedures of IVIS (NATS)
initialization and IVIS (NATS) ignition key ID registration, refer to CONSULT-II operation manual,
IVIS/NVIS.
Malfunction Indicator Lamp (MIL)UBS00GZU
DESCRIPTION
The MIL is located on the instrument panel.
1. The MIL will light up when the ignition switch is turned ON with-
out the engine running. This is a bulb check.
If the MIL does not light up, refer to DI-31, "
WAR NI NG L AMPS"
, or see EC-631, "MIL AND DATA LINK CONNECTOR" .
2. When the engine is started, the MIL should go off.
If the MIL remains on, the on board diagnostic system has
detected an engine system malfunction.
ON BOARD DIAGNOSTIC SYSTEM FUNCTION
The on board diagnostic system has the following 3 functions.
SEF 5 43 X
SEF 2 17 U

EC-64Revision: August 2007
ON BOARD DIAGNOSTIC (OBD) SYSTEM
2004 QX56
When there is an open circuit on MIL circuit, the ECM cannot warn the driver by lighting MIL up when there is
malfunction on engine control system.
Therefore, when electrical controlled throttle and part of ECM related diagnoses are continuously detected as
NG for 5 trips, ECM warns the driver that engine control system malfunctions and MIL circuit is open by means
of operating fail-safe function.
The fail-safe function also operates when above diagnoses except MIL circuit are detected, and demands the
driver to repair the malfunction.
HOW TO SWITCH DIAGNOSTIC TEST MODE
NOTE:

It is better to count the time accurately with a clock.

It is impossible to switch the diagnostic mode when an accelerator pedal position sensor circuit
has a malfunction.

Always ECM returns to Diagnostic Test Mode I after ignition switch is turned OFF.
How to Set Diagnostic Test Mode II (Self-diagnostic Results)
1. Confirm that accelerator pedal is fully released, turn ignition switch ON and wait 3 seconds.
2. Repeat the following procedure quickly five times within 5 seconds.
a. Fully depress the accelerator pedal.
b. Fully release the accelerator pedal.
3. Wait 7 seconds, fully depress the accelerator pedal and keep it for approx. 10 seconds until the MIL starts
blinking.
4. Fully release the accelerator pedal.
Diagnostic Test
ModeKEY and ENG.
Statu sFunction Explanation of Function
Mode I Ignition switch in
ON position
Engine stoppedBULB CHECK This function checks the MIL bulb for damage (blown,
open circuit, etc.).
If the MIL does not come on, check MIL circuit.
Engine running MALFUNCTION
WARNINGThis is a usual driving condition. When a malfunction is
detected twice in two consecutive driving cycles (two trip
detection logic), the MIL will light up to inform the driver
that a malfunction has been detected.
The following malfunctions will light up or blink the MIL in
the 1st trip.

Misfire (Possible three way catalyst damage)

One trip detection diagnoses
Mode II Ignition switch in
ON position
Engine stoppedSELF-DIAGNOSTIC
RESULTSThis function allows DTCs and 1st trip DTCs to be read.
Engine operating condition in fail-safe mode Engine speed will not rise more than 2,500 rpm due to the fuel cut