Nissan Qashqai J11. Manual - part 314

P0171 FUEL INJECTION SYSTEM FUNCTION

ECM-233

< DTC/CIRCUIT DIAGNOSIS >

[MR20DD]

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1.

Install all removed parts.

2.

Release fuel pressure to 0. Refer to 

ECM-135, "Work Procedure"

.

3.

Set a fuel pressure meter and check fuel pressure. Refer to 

ECM-135, "Work Procedure"

.

Is the inspection result normal?

YES

>> GO TO 6.

NO

>> GO TO 5.

5.

DETECT MALFUNCTIONING PART

Check fuel hoses and fuel tubes for clogging.

Is the inspection result normal?

YES

>> Replace “fuel filter and fuel pump assembly”. Refer to 

FL-19, "Removal and Installation"

.

NO

>> Repair or replace malfunctioning part.

6.

CHECK MASS AIR FLOW SENSOR

WITH CONSULT

1.

Install all removed parts.

2.

Start engine and warm it up to normal operating temperature.

3.

Check “MASS AIR FLOW” in “DATA MONITOR” mode with CONSULT.

*: Check for linear voltage rise in response to increase of engine speed.

WITHOUT CONSULT

1.

Install all removed parts.

2.

Start engine and warm it up to normal operating temperature.

3.

Check the voltage between ECM harness connector terminals under the following conditions.

*: Check for linear voltage rise in response to increase of engine speed.

Is the inspection result normal?

YES

>> GO TO 7.

NO

>> Check connectors for rusted terminals or loose connections in the mass air flow sensor circuit or

grounds. Refer to 

ECM-180, "Diagnosis Procedure"

.

7.

CHECK FUNCTION OF FUEL INJECTOR

WITH CONSULT

1.

Start engine.

2.

Perform “POWER BALANCE” in “ACTIVE TEST” mode with CONSULT.”

3.

Check that each circuit produces a momentary engine speed drop.

WITHOUT CONSULT

1.

Start engine and let it idle.

2.

Listen to each fuel injector operating sound.

At idle: 500 kPa (5.1 kg/cm

2

)

Monitor item

Condition

Indication

A/F SEN1 (B1)

Ignition switch ON (Engine stopped.)

Approx. 0.4 V

Idle (Engine is warmed-up to normal op-
erating temperature.)

0.7 - 1.2 V

Idle to about 4,000 rpm

0.7 -1.2 V 

→

 2.4 V*

ECM

Condition

Voltage

Connector

+

–

Terminal

F16

64

72

Ignition switch ON (Engine stopped.)

Approx. 0.4 V

Idle (Engine is warmed-up to normal 
operating temperature.)

0.7 -1.2 V

Idle to about 4,000 rpm

0.7 -1.2 V 

→

 2.4 V*

ECM-234

< DTC/CIRCUIT DIAGNOSIS >

[MR20DD]

P0171 FUEL INJECTION SYSTEM FUNCTION

Is the inspection result normal?

YES

>> GO TO 8.

NO

>> Perform trouble diagnosis for fuel injector and circuit,

refer to 

ECM-372, "Diagnosis Procedure"

.

8.

CHECK FUEL INJECTOR

1.

Turn ignition switch OFF.

2.

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

3.

Remove fuel tube assembly. Refer to 

EM-164, "Exploded View"

.

Keep fuel hose and all fuel injectors connected to fuel tube.

4.

The fuel injector harness connectors should remain connected.

5.

Disconnect all ignition coil harness connectors.

6.

Prepare pans or saucers under each fuel injector.

7.

Crank engine for about 3 seconds.

Is the inspection result normal?

YES

>> INSPECTION END

NO

>> Replace fuel injectors from which fuel does not spray

out evenly. Refer to 

EM-164, "Removal and Installation"

.

Always replace O-ring with new ones.

Clicking sound should 
be heard.

PBIB3332E

Fuel should be sprayed evenly for each fuel injec-
tor.

PBIA8556J

P0172 FUEL INJECTION SYSTEM FUNCTION

ECM-235

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P0172 FUEL INJECTION SYSTEM FUNCTION

DTC Description

INFOID:0000000010702940

DTC DETECTION 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 A/F sensor 1. The ECM calculatesthe
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 illuminates the MIL (2 trip detection
logic).

POSSIBLE CAUSE

• A/F sensor 1
• Fuel injector
• Exhaust gas leakage
• Incorrect fuel pressure
• Mass air flow sensor

FAIL-SAFE

DTC CONFIRMATION PROCEDURE

1.

PRECONDITIONING

If DTC Confirmation Procedure has been previously conducted, always turn ignition switch OFF and wait at
least 10 seconds before conducting the next test.

>> GO TO 2.

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.

CONSULT screen terms

(Trouble diagnosis content)

DTC detecting condition

P0172

FUEL SYS-RICH-B1
(System too rich bank 1)

• Fuel injection system does not operate properly.
• The amount of mixture ratio compensation is too large. (The mixture ratio 

is too rich.)

Engine operating condition in fail-safe mode

Fail safe mode

Vehicle behavior

Traveling con-
trol mode

Accelerator an-
gle variation 
control

ECM controls the accelerator pedal depression speed to make it slower than actual speed. This 
causes a drop in accelerating performance and encourages the driver to repair malfunction.
NOTE:
ECM does not control the accelerator pedal releasing speed.

Combustion 
control mode

Stratified charge 
combustion 
control at start-
ing

No stratified charge combustion at starting (cold start).

Idle speed con-
trol

Stops feedback control of idle speed and controls with specified speed.

Recovery speed 
control at decel-
erating

Stops recovery speed control by the fuel cut at decelerating and controls with specified speed.

Idle neutral con-
trol

Stops idle neutral control.

ECM-236

< DTC/CIRCUIT DIAGNOSIS >

[MR20DD]

P0172 FUEL INJECTION SYSTEM FUNCTION

2.

PERFORM DTC CONFIRMATION PROCEDURE-I

1.

Clear the mixture ratio self-learning value. Refer to 

ECM-131, "Work Procedure"

.

2.

Start engine.

Is it difficult to start engine?

YES

>> GO TO 3.

NO

>> GO TO 4.

3.

RESTART ENGINE

If it is difficult to start engine, the fuel injection system has a malfunction, too.
Crank engine while depressing accelerator pedal.

Does engine start?

YES

>> Proceed to 

ECM-236, "Diagnosis Procedure"

.

NO

>> Remove spark plugs and check for fouling, etc.

4.

PERFORM DTC CONFIRMATION PROCEDURE-II

1.

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

Is 1st trip DTC detected?

YES

>> Proceed to 

ECM-236, "Diagnosis Procedure"

.

NO

>> GO TO 5.

5.

PERFORM DTC CONFIRMATION PROCEDURE-III

1.

Turn ignition switch OFF and wait at least 10 seconds.

2.

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.

3.

Check 1st trip DTC.

Is 1st trip DTC detected?

YES

>> Proceed to 

ECM-236, "Diagnosis Procedure"

.

NO-1

>> To check malfunction symptom before repair: Refer to 

GI-41, "Intermittent Incident"

.

NO-2

>> Confirmation after repair: INSPECTION END

Diagnosis Procedure

INFOID:0000000010702941

1.

CHECK EXHAUST GAS LEAKAGE

1.

Start engine and run it at idle.

2.

Listen for an exhaust gas leakage before three way catalyst (manifold).

Is exhaust gas leakage detected?

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).

PBIB1216E