Infiniti Q45. Manual - part 419

DTC P0139, P0159 HO2S2

EC-315

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 0.78V at least once during this
procedure.
If the voltage is above 0.78V at step 6, step 7 is not neces-
sary.

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.

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 Installation

NBS001V5

HEATED OXYGEN SENSOR 2

Refer to

EX-3, "EXHAUST SYSTEM"

PBIB2024E

EC-316

DTC P0171, P0174 FUEL INJECTION SYSTEM FUNCTION

PFP:16600

On Board Diagnosis Logic

NBS001V6

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 air fuel ratio (A/F) sensor 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

NBS001V7

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

Start engine and warm it up to normal operating temperature.

Turn ignition switch OFF and wait at least 10 seconds.

Turn ignition switch ON and select “SELF-LEARNING CONT” in “WORK SUPPORT” mode with CON-
SULT-II.

Clear the self-learning control coefficient by touching “CLEAR”.

Select “DATA MONITOR” mode with CONSULT-II.

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-322, "Diagnostic

Procedure"

NOTE:
If 1st trip DTC is not detected during above procedure, perform-
ing the following procedure is advised.

Turn ignition switch OFF and wait at least 10 seconds.

Start engine and drive the vehicle under the similar conditions to
(1st trip) Freeze Frame Data for 10 minutes. Refer to the table below.
Hold the accelerator pedal as steady as possible.

The similar conditions to (1st trip) Freeze Frame Data means the vehicle operation that the following con-
ditions should be satisfied at the same time.

Sensor

Input Signal to ECM

ECM function

Actuator

A/F 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

●

A/F 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

Engine speed

Engine speed in the freeze frame data

400 rpm

Vehicle speed

Vehicle speed in the freeze frame data

10 km/h (6 MPH)

DTC P0171, P0174 FUEL INJECTION SYSTEM FUNCTION

EC-317

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

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

EC-322, "Diagnostic Procedure"

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

WITH GST

Start engine and warm it up to normal operating temperature.

Turn ignition switch OFF and wait at least 10 seconds.

Disconnect mass air flow sensor harness connector.

Restart engine and let it idle for at least 5 seconds.

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

Select Service $03 with GST. Make sure DTC P0102 is
detected.

Select Service $04 with GST and erase the DTC P0102.

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

Select Service $07 with GST. The 1st trip DTC P0171 or P0174
should be detected at this stage, if a malfunction exists. If so, go
to

EC-322, "Diagnostic Procedure"

NOTE:
If 1st trip DTC is not detected during above procedure, performing the following procedure is advised.

Turn ignition switch OFF and wait at least 10 seconds.

Start engine and drive the vehicle under the similar conditions to (1st trip) Freeze Frame Data for 10 min-
utes. Refer to the table below.
Hold the accelerator pedal as steady as possible.

The similar conditions to (1st trip) Freeze Frame Data means the vehicle operation that the following con-
ditions should be satisfied at the same time.

10. If it is difficult to start engine at step 8, the fuel injection system has a malfunction.

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

EC-322, "Diagnostic Procedure"

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

Engine coolant temperature
(T) condition

When the freeze frame data shows lower than 70

C (158

F),

T should be lower than 70

C (158

F).

When the freeze frame data shows higher than or equal to 70

C (158

F),

T should be higher than or equal to 70

C (158

F).

PBIB2418E

Engine speed

Engine speed in the freeze frame data

400 rpm

Vehicle speed

Vehicle speed in the freeze frame data

10 km/h (6 MPH)

Engine coolant temperature
(T) condition

When the freeze frame data shows lower than 70

C (158

F),

T should be lower than 70

C (158

F).

When the freeze frame data shows higher than or equal to 70

C (158

F),

T should be higher than or equal to 70

C (158

F).

EC-318

DTC P0171, P0174 FUEL INJECTION SYSTEM FUNCTION

Wiring Diagram

NBS001V8

BANK 1

TBWM1228E

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