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Infiniti Q45 (FY33). Manual - part 180

SEF099P

SEF054TI

SEF056TH

SEF409WA

SEF390UA

DIAGNOSTIC PROCEDURE

INSPECTION START

CHECK EXHAUST AIR LEAK.
Start engine and run it at idle. Listen for an
exhaust air leak before three way catalyst.

Repair or replace.

CHECK FOR INTAKE AIR LEAK.
Start engine and run it at idle. Listen for an
intake air leak between the mass air flow sensor
and the intake manifold.

Repair or replace.

CHECK HEATED OXYGEN SENSOR 1
(FRONT).
1. Turn ignition switch “OFF”.

2. Disconnect heated oxygen sensor 1 (front)

harness connector and ECM harness connec-
tor.

3. Check harness continuity between ECM and

sensor terminals.

Continuity should exist.

4. Check harness continuity between ECM and

sensor or ground.

Continuity should not exist.
If OK, check harness for short to ground and
short to power.

Repair harness or connectors.

CHECK FUEL PRESSURE.
1. Release fuel pressure to zero. Refer to

EC-37.

2. Install fuel pressure gauge and check fuel

pressure.
At idle:

Approx. 235 kPa
(2.4 kg/cm

, 34 psi)

A few seconds after ignition switch is
turned OFF to ON:

Approx. 294 kPa
(3.0 kg/cm

, 43 psi)

Check the following.

Fuel pump and circuit
Refer to EC-523.

Fuel pressure regulator
Refer to EC-37.

Fuel lines
Refer to EC-38.

Fuel lines
Refer to “ENGINE MAINTE-
NANCE” in MA section.

Fuel filter for clogging

If NG, repair or replace.

CHECK MASS AIR FLOW SENSOR.

Check “MASS AIR FLOW” in “DATA
MONITOR” mode with CONSULT-II.
3.0 - 6.0 g

⋅

m/sec: at idling

12.9 - 25.3 g

⋅

m/sec: at 2,500 rpm

---------------------------------------------------------------------------------------------------------------------------------------- OR ----------------------------------------------------------------------------------------------------------------------------------------

Check “mass air flow” in MODE 1 with
GST.
3.0 - 6.0 g

⋅

m/sec: at idling

12.9 - 25.3 g

⋅

m/sec: at 2,500 rpm

Check mass air flow sensor output
voltage, refer to EC-131.
Approximately 2.1V: at 2,500 rpm

Check connectors for rusted
terminals or loose connections
in the mass air flow sensor cir-
cuit or engine grounds. Refer to
EC-124.

(Go to next page.)

DTC

Terminals

Bank

(Harness

protector

color)

ECM

Sensor

P0171

(B1) (Black)

P0174

(B2) (Blue)

DTC

Terminals

Bank

(Harness

protector

color)

ECM or

sensor

Ground

P0171

83 or 2

Ground

(B1) (Black)

P0174

82 or 2

Ground

(B2) (Blue)

IDX

TROUBLE DIAGNOSIS FOR DTC P0171 (B1), P0174 (B2)

Fuel Injection System Function (Lean side)
(P0171: Bank 1), (P0174: Bank 2) (Cont’d)

EC-249

SEF793X

MEC703B

SEF595Q

CHECK FUNCTION OF INJECTORS.
1. Install all parts removed.

2. Start engine.

3. Perform “POWER BALANCE” in

“ACTIVE TEST” mode with CON-
SULT-II.

4. Make sure that each circuit pro-

duces a momentary engine
speed drop.

-------------------------------------------------------------------------------------------------------------------------------------- OR --------------------------------------------------------------------------------------------------------------------------------------

3. Listen to each injector operating

sound.
Clicking noise should be
heard.

Perform TROUBLE DIAG-
NOSIS FOR NON-DE-
TECTABLE ITEMS,
“Injectors”, EC-515.
Repair harness or connec-
tors.

Confirm that the engine is cooled down
and there are no fire hazards near the
vehicle.

1. Turn ignition switch “OFF”.

2. Remove injector gallery assembly.

Refer to EC-38.
Keep fuel hose and all injectors con-
nected to injector gallery.
The injector harness connectors should
remain connected.

1. Disconnect all ignition coil harness con-

nectors.

2. Place pans or saucers under each injec-

tor.

3. Crank engine for about 3 seconds. Make

sure that fuel sprays out vigorously from
injectors.
Fuel should be sprayed evenly for
each cylinder.

Replace injectors from
which fuel does not spray
out. Always replace O-ring
with new one.

Perform “TROUBLE DIAGNOSIS FOR
INTERMITTENT INCIDENT”, EC-117.

INSPECTION END

TROUBLE DIAGNOSIS FOR DTC P0171 (B1), P0174 (B2)

Fuel Injection System Function (Lean side)
(P0171: Bank 1), (P0174: Bank 2) (Cont’d)

EC-250

Fuel Injection System Function (Rich side)
(P0172: Left bank), (P0175: Right bank)

ON BOARD DIAGNOSIS LOGIC

With the Air/Fuel Mixture Ratio Self-Learning Control, the actual mixture ratio can be brought closely to the
theoretical mixture ratio based on the mixture ratio feedback signal from the heated oxygen sensor 1 (front).
The ECM calculates the necessary compensation to correct the offset between the actual and the theoretical
ratios.
In case the amount of the compensation value is extremely large (The actual mixture ratio is too rich.), the
ECM judges the condition as the fuel injection system malfunction and light up the MIL (2 trip detection logic).

Heated oxygen sensor 1 (front)

Density of oxygen in exhaust gas

(Mixture ratio feedback signal)

ECM

Injectors

Diagnostic Trouble

Code No.

Malfunction is detected when ...

Check Items

(Possible Cause)

P0172
0114
(Bank 1)

Fuel injection system does not operate properly.

The amount of mixture ratio compensation is too large. (The
mixture ratio is too rich.)

Heated oxygen sensor 1 (front)

Injectors

Exhaust gas leaks

Incorrect fuel pressure

Mass air flow sensor

P0175
0209
(Bank 2)

SEF985Z

SEC042C

DIAGNOSTIC TROUBLE CODE CONFIRMATION
PROCEDURE

NOTE:
If “DIAGNOSTIC TROUBLE CODE CONFIRMATION PROCE-
DURE” has been previously conducted, always turn ignition
switch “OFF” and wait at least 5 seconds before conducting
the next test.

1) Start engine and warm it up to normal operating tem-

perature.

2) Turn ignition switch “OFF” and wait at least 5 seconds.
3) Turn ignition switch “ON” and select “SELF-LEARN

CONTROL” in “WORK SUPPORT” mode with CON-
SULT-II.

4) Clear the self-learning control coefficient by touching

“CLEAR”.

5) Select “DATA MONITOR” mode with CONSULT-II.
6) Start engine again and let it idle for at least 10 minutes.

The 1st trip DTC P0172 should be detected at this
stage, if a malfunction exists. If so, go to “DIAGNOSTIC
PROCEDURE”, EC-255.

7) If it is difficult to start engine at step 6), the fuel injec-

tion system has a malfunction.

8) Crank engine while depressing accelerator pedal. If

engine starts, go to “DIAGNOSTIC PROCEDURE”,
EC-255. If engine does not start, remove ignition plugs
and check for fouling, etc.

------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ OR ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

IDX

TROUBLE DIAGNOSIS FOR DTC P0172 (B1), P0175 (B2)

EC-251

SEF395W

1) Start engine and warm it up to normal operating tem-

perature.

2) Turn ignition switch “OFF” and wait at least 5 seconds.
3) Disconnect mass air flow sensor harness connector.

Then restart and run engine for at least 3 seconds at
idle speed.

4) Stop engine and reconnect mass air flow sensor har-

ness connector.

5) Select “MODE 7” with GST. Make sure 1st trip DTC

P0100 is detected.

6) Select “MODE 4” with GST and erase the 1st trip DTC

P0100.

7) Start engine again and run it for at least 10 minutes at

idle speed.

8) Select “MODE 7” with GST. The 1st trip DTC P0171

should be detected at this stage, if a malfunction exists.
If so, go to “DIAGNOSTIC PROCEDURE”, EC-255.

9) If it is difficult to start engine at step 8, the fuel injection

system has a malfunction.

10) Crank engine while depressing accelerator pedal. If

engine starts, go to “DIAGNOSTIC PROCEDURE”,
EC-255. If engine does not start, remove ignition plugs
and check for fouling, etc.

1) Start engine and warm it up to normal operating tem-

perature.

2) Turn ignition switch “OFF” and wait at least 5 seconds.
3) Disconnect mass air flow sensor harness connector.
4) Then restart engine and run it for at least 3 seconds at

idle speed.

5) Stop engine and reconnect mass air flow sensor har-

ness connector.

6) Turn ignition switch “ON”.
7) Perform “Diagnostic Test Mode II (Self-diagnostic

results)” with ECM. Make sure DTC 0102 is detected.

8) Erase the DTC 0102 by changing from Diagnostic Test

Mode II to Diagnostic Test Mode I.

9) Perform “Diagnostic Test Mode II (Self-diagnostic

results)” with ECM. Make sure DTC 0505 is detected.

10) Start engine again and run it for at least 10 minutes at

idle speed.
The DTC 0114 should be detected at this stage, if a
malfunction

exists.

so,

“DIAGNOSTIC

PROCEDURE”, EC-255.

11) If it is difficult to start engine at step 10, the fuel injec-

tion system also has a malfunction.

12) Crank engine while depressing accelerator pedal. If

engine starts, go to “DIAGNOSTIC PROCEDURE”,
EC-255. If engine does not start, remove ignition plugs
and check for fouling, etc.

TROUBLE DIAGNOSIS FOR DTC P0172 (B1), P0175 (B2)

Fuel Injection System Function (Rich side)
(P0172: Left bank), (P0175: Right bank)
(Cont’d)

EC-252

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