Nissan X-Trail 32. Manual - part 880

P014C, P014D A/F SENSOR 1

EC-649

< DTC/CIRCUIT DIAGNOSIS >

[QR25DE]

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6.

Increase the engine speed up to about 3,600 rpm and keep it for 10 seconds.

7.

Fully release accelerator pedal and then let engine idle for about 1 minute.

8.

Check 1st trip DTC.

Is 1st trip DTC detected?

YES

>> Proceed to 

EC-649, "Diagnosis Procedure"

.

NO

>> INSPECTION END

Diagnosis Procedure

INFOID:0000000010986350

1.

RETIGHTEN A/F SENSOR 1

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

EM-180, "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 (manifold).

Is exhaust gas leak detected?

YES

>> Repair or replace.

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.

NO

>> GO TO 4.

4.

CLEAR THE MIXTURE RATIO SELF-LEARNING VALUE

1.

Clear the mixture ratio self-learning value. Refer to 

EC-557, "Work Procedure"

.

2.

Run engine for at least 10 minutes at idle speed.

Is the 1st trip DTC P0171 or P172 detected? Is it difficult to start engine?

YES

>> Perform trouble diagnosis for DTC P0171 or P0172. Refer to 

EC-652, "DTC Description"

 or 

EC-

657, "DTC Description"

.

NO

>> GO TO 5.

5.

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

1.

Disconnect A/F sensor 1 harness connector.

2.

Turn ignition switch ON.

3.

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

Is the inspection result normal?

PBIB1216E

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–

Voltage

A/F sensor 1

Connector

Terminal

F27

4

Ground

Battery voltage

EC-650

< DTC/CIRCUIT DIAGNOSIS >

[QR25DE]

P014C, P014D A/F SENSOR 1

YES

>> GO TO 6.

NO

>> Repair or replace error-detected parts.

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.

4.

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

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

Refer to 

EC-593, "Component Inspection"

.

Is the inspection result normal?

YES

>> GO TO 8.

NO

>> GO TO 11.

8.

CHECK MASS AIR FLOW SENSOR

Refer to 

EC-607, "Component Inspection"

.

Is the inspection result normal?

YES

>> GO TO 9. 

NO

>> Replace mass air flow sensor. Refer to 

EM-174, "Exploded View"

.

9.

CHECK PCV VALVE

Refer to 

EC-805, "Inspection"

.

Is the inspection result normal?

YES

>> GO TO 10.

NO

>> Repair or replace PCV valve. Refer to 

EC-440, "Component Parts Location"

.

10.

CHECK INTERMITTENT INCIDENT

Perform 

GI-44, "Intermittent Incident"

.

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Continuity

A/F sensor 1

ECM

Connector

Terminal

Connector

Terminal

F27

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F85

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Existed

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–

Continuity

A/F sensor 1

Connector

Terminal

F27

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Ground

Not existed

2

+

–

Continuity

ECM

Connector

Terminal

F85

41

Ground

Not existed

45

P014C, P014D A/F SENSOR 1

EC-651

< DTC/CIRCUIT DIAGNOSIS >

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Is the inspection result normal?

YES

>> GO TO 11.

NO

>> Repair or replace.

11.

REPLACE AIR FUEL RATIO (A/F) SENSOR 1

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

EM-180, "Exploded View"

.

CAUTION:

• Discard any 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 sensor, clean exhaust system threads using Oxygen Sensor Thread Cleaner

[commercial service tool (J-43897-18 or J43897-12)] and approved Anti-seize Lubricant (commercial
service tool).

>> INSPECTION END

EC-652

< DTC/CIRCUIT DIAGNOSIS >

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P0171 FUEL INJECTION SYSTEM FUNCTION

P0171 FUEL INJECTION SYSTEM FUNCTION

DTC Description

INFOID:0000000010986351

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).

POSSIBLE CAUSE

• 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

FAIL-SAFE

Traveling control mode (Accelerator angle variation control)

DTC CONFIRMATION PROCEDURE

1.

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.

2.

PERFORM DTC CONFIRMATION PROCEDURE-1

1.

Clear the mixture ratio self-learning value. Refer to 

EC-557, "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.
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?

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

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.)