Infiniti M45 (Y34). Manual - part 396

DTC P0171, P0174 FUEL INJECTION SYSTEM FUNCTION

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8. 

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 9.

NG

>> Perform trouble diagnosis for 

EC-661, "INJECTOR CIRCUIT"

 .

9. 

CHECK INJECTOR

1.

Turn ignition switch OFF.

2.

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

3.

Disconnect all injector harness connectors.

4.

Remove injector gallery assembly. Refer to 

EM-31, "FUEL INJECTOR AND FUEL TUBE"

 .

Keep fuel hose and all injectors connected to injector gallery.

5.

For DTC P0171, reconnect injector harness connectors on bank 1.
For DTC P0174, reconnect injector harness connectors on bank 2.

6.

Disconnect all ignition coil harness connectors.

7.

Prepare pans or saucers under each injector.

8.

Crank engine for about 3 seconds.
For DTC P0171, make sure that fuel sprays out from injectors
on bank 1.
For DTC P0174, make sure that fuel sprays out from injectors
on bank 2.

OK or NG

OK

>> GO TO 10.

NG

>> Replace injectors from which fuel does not spray out.

Always replace O-ring with new ones.

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Clicking noise should be heard.

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Fuel should be sprayed evenly for each injector.

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EC-274

DTC P0171, P0174 FUEL INJECTION SYSTEM FUNCTION

10. 

CHECK INTERMITTENT INCIDENT

Refer to 

EC-132, "TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT"

 .

>> INSPECTION END

DTC P0172, P0175 FUEL INJECTION SYSTEM FUNCTION

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DTC P0172, P0175 FUEL INJECTION SYSTEM FUNCTION

PFP:16600

On Board Diagnosis Logic

ABS002HY

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 sensors 1. 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 lights up the MIL (2 trip detection logic).

DTC Confirmation Procedure

ABS002HZ

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

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 and select “SELF-LEARNING CONT” 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 or P0175 should be detected at this
stage, if a malfunction exists. If so, go to 

EC-279, "Diagnostic

Procedure"

 .

7.

If it is difficult to start engine at step 6, the fuel injection system
has a malfunction, too.

8.

Crank engine while depressing accelerator pedal.
If engine starts, go to 

EC-279, "Diagnostic Procedure"

 . If engine

does not start, remove ignition plugs and check for fouling, etc.

Sensor

Input Signal to ECM

ECM function

Actuator

Heated oxygen sensor 1

Density of oxygen in exhaust gas
(Mixture ratio feedback signal)

Fuel injection control

Fuel injector

DTC No.

Trouble diagnosis name

DTC detecting condition

Possible cause

P0172
0172
(Bank 1)

Fuel injection system too 
rich

●

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

●

Fuel injector

●

Exhaust gas leaks

●

Incorrect fuel pressure

●

Mass air flow sensor

P0175
0175
(Bank 2)

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DTC P0172, P0175 FUEL INJECTION SYSTEM FUNCTION

 WITH GST

1.

Start engine and warm it up to normal operating temperature.

2.

Turn ignition switch OFF and wait at least 10 seconds.

3.

Disconnect mass air flow sensor harness connector. Then
restart and let engine idle for at least 5 seconds.

4.

Stop engine and reconnect mass air flow sensor harness con-
nector.

5.

Select “MODE 3” with GST. Make sure DTC P0102 is detected.

6.

Select “MODE 4” with GST and erase the DTC P0102.

7.

Start engine again and let it idle for at least 10 minutes.

8.

Select “MODE 7” with GST. The 1st trip DTC P0172 or P0175
should be detected at this stage, if a malfunction exists. If so, go
to 

EC-279, "Diagnostic Procedure"

 .

9.

If it is difficult to start engine at step 7, the fuel injection system
has a malfunction.

10. Crank engine while depressing accelerator pedal.

If engine starts, go to 

EC-279, "Diagnostic Procedure"

 . If engine does not start, remove ignition plugs and

check for fouling, etc.

PBIB1119E