Content .. 385 386 387 388 ..

Nissan Sentra. Manual - part 387

EC-244

< DTC/CIRCUIT DIAGNOSIS >

[MRA8DE]

P014C, P014D, P015A, P015B A/F SENSOR 1

*: Check for linear voltage rise in response to engine being increased to about 4,000 rpm.

Without CONSULT

1. Repair or replace malfunctioning part.

2. Start engine and warm it up to normal operating temperature.

3. Check the voltage between ECM harness connector and ground.

*: Check for linear voltage rise in response to engine being increased to about 4,000 rpm.

Is the inspection result normal?

YES

>> INSPECTION END

>> GO TO 4.

CHECK MASS AIR FLOW SENSOR-3

With CONSULT

1. Turn ignition switch OFF.

2. Disconnect mass air flow sensor harness connector and reconnect it again.

3. Start engine and warm it up to normal operating temperature.

4. Connect CONSULT and select “DATA MONITOR” mode of “ENGINE”.

5. Select “MAS A/F SE-B1” and check indication.

*: Check for linear voltage rise in response to engine being increased to about 4,000 rpm.

Without CONSULT

1. Turn ignition switch OFF.

2. Disconnect mass air flow sensor harness connector and reconnect it again.

3. Start engine and warm it up to normal operating temperature.

4. Check the voltage between ECM harness connector and ground.

Monitor item

Condition

Value

MAS A/F SE-B1

Ignition switch ON (Engine stopped.)

Approx. 1.3 V

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

1.3 - 1.6 V

2,500 rpm (Engine is warmed-up to normal
operating temperature.)

1.8 - 2.2 V

Idle to about 4,000 rpm

1.3 - 1.6 V to Ap-

prox. 2.5 V*

ECM

Condition

Voltage

Connector

−

Terminal

F24

Ignition switch ON (Engine
stopped.)

Approx. 1.3 V

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

1.3 - 1.6 V

2,500 rpm (Engine is warmed-up to
normal operating temperature.)

1.8 - 2.2 V

Idle to about 4,000 rpm

1.3 - 1.6 V to Ap-

prox. 2.5 V*

Monitor item

Condition

Value

MAS A/F SE-B1

Ignition switch ON (Engine stopped.)

Approx. 1.3 V

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

1.3 - 1.6 V

2,500 rpm (Engine is warmed-up to normal
operating temperature.)

1.8 - 2.2 V

Idle to about 4,000 rpm

1.3 - 1.6 V to Ap-

prox. 2.5 V*

P014C, P014D, P015A, P015B A/F SENSOR 1

EC-245

< DTC/CIRCUIT DIAGNOSIS >

[MRA8DE]

*: Check for linear voltage rise in response to engine being increased to about 4,000 rpm.

Is the inspection result normal?

YES

>> INSPECTION END

>> Clean or replace mass air flow sensor. Refer to

EM-25, "Exploded View"

ECM

Condition

Voltage

Connector

−

Terminal

F24

Ignition switch ON (Engine
stopped.)

Approx. 1.3 V

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

1.3 - 1.6 V

2,500 rpm (Engine is warmed-up to
normal operating temperature.)

1.8 - 2.2 V

Idle to about 4,000 rpm

1.3 - 1.6 V to Ap-

prox. 2.5 V*

EC-246

< DTC/CIRCUIT DIAGNOSIS >

[MRA8DE]

P0171 FUEL INJECTION SYSTEM FUNCTION

P0171 FUEL INJECTION SYSTEM FUNCTION

DTC Logic

INFOID:0000000009758498

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 the A/F sensors 1. The ECM calcu-

lates 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

PRECONDITIONING

If DTC Confirmation Procedure has been previously conducted, always perform the following procedure

before conducting the next test.

1. Turn ignition switch OFF and wait at least 10 seconds.

2. Turn ignition switch ON.

3. Turn ignition switch OFF and wait at least 10 seconds.

>> GO TO 2.

PERFORM DTC CONFIRMATION PROCEDURE-1

1. Clear the mixture ratio self-learning value. Refer to

EC-142, "Work Procedure"

2. Start engine.
Is it difficult to start engine?

YES

>> GO TO 3.

>> GO TO 4.

RESTART ENGINE

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

Crank engine while depressing accelerator pedal.

NOTE:

When depressing accelerator pedal three-fourths (3/4) or more, the control system does not start the

engine. Do not depress accelerator pedal too much.
Does engine start?

YES

>> Proceed to

EC-247, "Diagnosis Procedure"

>> Check exhaust and intake air leak visually.

PERFORM DTC CONFIRMATION PROCEDURE-2

1. Start engine and let it idle for at least 5 minutes.

2. Check 1st trip DTC.

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 con-

tent)

DTC detecting condition

Possible cause

P0171

FUEL SYS-LEAN-B1
(System too lean bank 1)

• 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

P0171 FUEL INJECTION SYSTEM FUNCTION

EC-247

< DTC/CIRCUIT DIAGNOSIS >

[MRA8DE]

Is 1st trip DTC detected?

YES

>> Proceed to

EC-247, "Diagnosis Procedure"

>> GO TO 5.

PERFORM DTC CONFIRMATION PROCEDURE-3

1. Turn ignition switch OFF and wait at least 10 seconds.

2. Start engine.

3. Maintain the following conditions for at least 10 consecutive minutes.

Hold the accelerator pedal as steady as possible.

CAUTION:

Always drive vehicle at a safe speed.

4. Check 1st trip DTC.
Is 1st trip DTC detected?

YES

>> Proceed to

EC-247, "Diagnosis Procedure"

>> INSPECTION END

Diagnosis Procedure

INFOID:0000000009758499

CHECK EXHAUST GAS LEAK

1. Start engine and run it at idle.

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

Is exhaust gas leak detected?

YES

>> Repair or replace error-detected parts.

>> GO TO 2.

CHECK FOR INTAKE AIR LEAK

1. Listen for an intake air leak after the mass air flow sensor.

2. Check PCV hose connection.
Intake air leak detected?

YES

>> Repair or replace error-detected parts.

>> GO TO 3.

CHECK A/F SENSOR 1 INPUT SIGNAL CIRCUIT

1. Turn ignition switch OFF.

2. Disconnect corresponding A/F sensor 1 harness connector.

3. Disconnect ECM harness connector.

4. Check the continuity between A/F sensor 1 harness connector and ECM harness connector.

*1: Except California

VHCL SPEED SE

50 - 120 km/h (31 - 75 MPH)

PBIB1216E

−

Continuity

A/F sensor 1

ECM

Connector

Terminal

Connector

Terminal

F12

F42

F24

Existed

Content .. 385 386 387 388 ..