Infiniti M45 (Y34). Manual - part 394

DTC P0139, P0159 HO2S2

EC-265

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EC

Removal and Installation

ABS002HT

HEATED OXYGEN SENSOR 2

Refer to 

EM-22, "EXHAUST MANIFOLD AND THREE WAY CATALYST"

 .

EC-266

DTC P0171, P0174 FUEL INJECTION SYSTEM FUNCTION

DTC P0171, P0174 FUEL INJECTION SYSTEM FUNCTION

PFP:16600

On Board Diagnosis Logic

ABS002HU

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 lean.), the
ECM judges the condition as the fuel injection system malfunction and lights up the MIL (2 trip detection logic).

DTC Confirmation Procedure

ABS002HV

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 P0171 or P0174 should be detected at this
stage, if a malfunction exists. If so, go to 

EC-270, "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-270, "Diagnostic Procedure"

 . If engine does not

start, check exhaust and intake air leak visually.

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

P0171
0171
(Bank 1)

Fuel injection system too 
lean

●

Fuel injection system does not operate properly.

●

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

●

Intake air leaks

●

Heated oxygen sensor 1

●

Fuel injector

●

Exhaust gas leaks

●

Incorrect fuel pressure

●

Lack of fuel

●

Mass air flow sensor

●

Incorrect PCV hose connection

P0174
0174
(Bank 2)

SEF968Y

DTC P0171, P0174 FUEL INJECTION SYSTEM FUNCTION

EC-267

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 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 P0171 or P0174
should be detected at this stage, if a malfunction exists. If so, go
to 

EC-270, "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-270, "Diagnostic Procedure"

 .

If engine does not start, check exhaust and intake air leak visually.

PBIB1119E

EC-268

DTC P0171, P0174 FUEL INJECTION SYSTEM FUNCTION

Wiring Diagram

ABS002HW

BANK 1

TBWA0278E