Nissan Sentra. Manual - part 386

EC-240

< DTC/CIRCUIT DIAGNOSIS >

[MRA8DE]

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

Diagnosis Procedure

INFOID:0000000009758495

1.

RETIGHTEN A/F SENSOR 1

Loosen and retighten the A/F sensor 1. Refer to 

EM-30, "Exploded View"

.

>> GO TO 2.

2.

CHECK EXHAUST GAS LEAK

1. Start engine and run it at idle.

2. Listen for an exhaust gas leak before three way catalyst 1.

Is exhaust gas leak detected?

YES

>> Repair or replace error-detected parts.

NO

>> GO TO 3.

3.

CHECK FOR INTAKE AIR LEAK

Listen for an intake air leak after the mass air flow sensor.
Is intake air leak detected?

YES

>> Repair or replace error-detected parts.

NO

>> GO TO 4.

4.

CLEAR THE MIXTURE RATIO SELF-LEARNING VALUE

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

EC-142, "Work Procedure"

.

2. Run engine for at least 10 minutes at idle speed.
Is the 1st trip DTC P0171 or P0172 detected? Is it difficult to start engine?

YES

>> • Perform trouble diagnosis for DTC P0171. Refer to 

EC-246, "DTC Logic"

.

• Perform trouble diagnosis for DTC P0172. Refer to 

EC-250, "DTC Logic"

.

NO

>> GO TO 5.

5.

CHECK AIR FUEL RATIO (A/F) SENSOR 1 POWER SUPPLY

1. Turn ignition switch OFF.

2. Disconnect A/F sensor 1 harness connector.

3. Turn ignition switch ON.

4. Check the voltage between A/F sensor 1 harness connector and ground.

*1: Except California

*2: For California

Is the inspection result normal?

YES

>> GO TO 6.

NO

>> GO TO 11.

PBIB1216E

+

−

Voltage

A/F sensor 1

Connector

Terminal

F12

*1

F42

*2

4

Ground

Battery voltage

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

EC-241

< DTC/CIRCUIT DIAGNOSIS >

[MRA8DE]

C

D

E

F

G

H

I

J

K

L

M

A

EC

N

P

O

6.

CHECK A/F SENSOR 1 INPUT SIGNAL CIRCUIT

1. Turn ignition switch OFF.

2. Disconnect ECM harness connector.

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

*1: Except California

*2: For California

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

and ground.

*1: Except California

*2: For California

5. Also check harness for short to power.
Is the inspection result normal?

YES

>> GO TO 7.

NO

>> Repair or replace error-detected parts.

7.

CHECK AIR FUEL RATIO (A/F) SENSOR 1 HEATER

Check the air fuel ratio (A/F) sensor 1 heater. Refer to 

EC-242, "Component Inspection (A/F Sensor 1

Heater)"

.

Is the inspection result normal?

YES

>> GO TO 8.

NO

>> Replace air fuel ratio (A/F) sensor 1. Refer to 

EM-30, "Exploded View"

.

8.

CHECK MASS AIR FLOW SENSOR

Check the mass air flow sensor. Refer to 

EC-242, "Component Inspection (MAF Sensor)"

.

Is the inspection result normal?

YES

>> GO TO 9. 

NO

>> Replace mass air flow sensor. Refer to 

EM-25, "Exploded View"

.

9.

CHECK PCV VALVE

Check the PCV valve. Refer to 

EC-484, "Inspection"

.

Is the inspection result normal?

YES

>> GO TO 10.

+

-

Continuity

A/F sensor 1

ECM

Connector

Terminal

Connector

Terminal

F12

*1

F42

*2

1

F24

41

Existed

2

45

+

−

Continuity

A/F sensor 1

Connector

Terminal

F12

*1

F42

*2

1

Ground

Not existed

2

+

−

Continuity

ECM

Connector

Terminal

F24

41

Ground

Not existed

45

EC-242

< DTC/CIRCUIT DIAGNOSIS >

[MRA8DE]

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

NO

>> Repair or replace PCV valve. Refer to 

EC-15, "ENGINE CONTROL SYSTEM :

Component Parts Location"

.

10.

CHECK INTERMITTENT INCIDENT

Check intermittent incident. Refer to 

GI-39, "Intermittent Incident"

.

Is the inspection result normal?

YES

>> Replace air fuel ratio (A/F) sensor 1. Refer to 

EM-30, "Exploded View"

.

NO

>> Repair or replace error-detected parts.

11.

CHECK AIR FUEL RATIO (A/F) SENSOR 1 POWER SUPPLY CIRCUIT

1. Turn ignition switch OFF.

2. Disconnect IPDM E/R harness connector.

3. Check the continuity between A/F sensor 1 harness connector and IPDM E/R harness connector.

*1: Except California

*2: For California

4. Also check harness for short to ground.
Is the inspection result normal?

YES

>> Perform the trouble diagnosis for power supply circuit.

NO

>> Repair or replace error-detected parts.

Component Inspection (A/F Sensor 1 Heater)

INFOID:0000000009758496

1.

CHECK AIR FUEL RATIO (A/F) SENSOR 1

1. Turn ignition switch OFF.

2. Disconnect A/F sensor 1 harness connector.

3. Check resistance between A/F sensor 1 terminals as per the following.

Is the inspection result normal?

YES

>> INSPECTION END

NO

>> Replace air fuel ratio (A/F) sensor 1. Refer to 

EM-30, "Exploded View"

.

Component Inspection (MAF Sensor)

INFOID:0000000009758497

1.

CHECK MASS AIR FLOW SENSOR-1

With CONSULT

1. Turn ignition switch OFF.

2. Reconnect all harness connectors disconnected.

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

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

+

−

Continuity

A/F sensor 1

IPDM E/R

Connector

Terminal

Connector

Terminal

F12

*1

F42

*2

4

E45

26

Existed

+

−

Resistance

A/F sensor 1

Terminal

3

4

1.8  -  2.44 

Ω [at 20°C (68°F)]

1

∞ Ω

(Continuity should not exist)

2

4

1

2

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

EC-243

< DTC/CIRCUIT DIAGNOSIS >

[MRA8DE]

C

D

E

F

G

H

I

J

K

L

M

A

EC

N

P

O

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. Reconnect all harness connectors disconnected.

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

4. 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

NO

>> GO TO 2.

2.

CHECK FOR THE CAUSE OF UNEVEN AIR FLOW THROUGH MASS AIR FLOW SENSOR

1. Turn ignition switch OFF.

2. Check for the cause of uneven air flow through mass air flow sensor. Refer to the following.

-

Crushed air ducts

-

Malfunctioning seal of air cleaner element

-

Uneven dirt of air cleaner element

-

Intake valve deposits

-

Improper specification of intake air system parts

Is the inspection result normal?

YES

>> GO TO 4.

NO

>> GO TO 3.

3.

CHECK MASS AIR FLOW SENSOR-2

With CONSULT

1. Repair or replace malfunctioning part.

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

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

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

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

35

34

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*