Nissan Pathfinder (2012 year). Manual - part 263

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

6. Keep engine at idle for at least 5 minutes.
7. Check 1st trip DTC.
8. The 1st trip DTC P0171 or P0174 should be detected at this stage, if a malfunction exists. If so, go to

186, "Diagnosis Procedure"

NOTE:

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

a. Turn ignition switch OFF and wait at least 10 seconds.
b. Start engine.
c. Maintain the following conditions for at least 10 consecutive minutes.

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
• Air fuel ratio (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)

August 2012

2012 Pathfinder

EC-186

< DTC/CIRCUIT DIAGNOSIS >

[VQ40DE]

P0171, P0174 FUEL INJECTION SYSTEM FUNCTION

Hold the accelerator pedal as steady as possible.

CAUTION:

Always drive vehicle at a safe speed.

d. Check 1st trip DTC.
e. If 1st trip DTC is detected, go to

WITH GST

1. Start engine and warm it up to normal operating temperature.
2. Turn ignition switch OFF and wait at least 10 seconds.
3. Disconnect mass air flow sensor harness connector.
4. Restart engine and let it idle for at least 5 seconds.
5. Stop engine and reconnect mass air flow sensor harness con-

nector.

6. Select Service $03 with GST. Check that DTC P0102 is

detected.

7. Select Service $04 with GST and erase the DTC P0102.
8. Start engine.

If it is difficult to start engine, the fuel injection system has a mal-

function.

Performing the following procedure is advised.

a. 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.

b. If engine starts, go to

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

9. Keep engine at idle for at least 5 minutes.
10. Check 1st trip DTC.
11. The 1st trip DTC P0171 or P0174 should be detected at this stage, if a malfunction exists. If so, go to

186, "Diagnosis Procedure"

NOTE:

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

a. Turn ignition switch OFF and wait at least 10 seconds.
b. Start engine.
c.

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.

d. Check 1st trip DTC.
e. If 1st trip DTC is detected, go to

EC-487, "Fuel Pressure Check"

Diagnosis Procedure

INFOID:0000000007358103

CHECK EXHAUST GAS LEAK

1. Start engine and run it at idle.

VHCL SPEED SE

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

VHCL SPEED SE

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

BBIA0541E

August 2012

2012 Pathfinder

P0171, P0174 FUEL INJECTION SYSTEM FUNCTION

EC-187

< DTC/CIRCUIT DIAGNOSIS >

[VQ40DE]

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

OK or NG

>> GO TO 2.

>> Repair or replace.

CHECK FOR INTAKE AIR LEAK

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

2. Check PCV hose connection.
OK or NG

>> GO TO 3.

>> Repair or replace.

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 harness continuity between A/F sensor 1 terminal and ECM terminal as follows.

Refer to Wiring Diagram.

5. Check harness continuity between the following terminals and ground.

Refer to Wiring Diagram.

PBIB1216E

A/F sensor 1 terminal

ECM terminal

Bank 1

Bank 2

Continuity should exist.

Bank 1

Bank 2

A/F sensor 1 terminal

ECM terminal

A/F sensor 1 terminal

ECM terminal

Continuity should not exist.

BBIA0544E

August 2012

2012 Pathfinder

EC-188

< DTC/CIRCUIT DIAGNOSIS >

[VQ40DE]

P0171, P0174 FUEL INJECTION SYSTEM FUNCTION

6. Also check harness for short to power.
OK or NG

>> GO TO 4.

>> Repair open circuit or short to ground or short to power in harness or connectors.

CHECK FUEL PRESSURE

1. Release fuel pressure to zero. Refer to

2. Install fuel pressure gauge and check fuel pressure. Refer to

EC-487, "Fuel Pressure Check"

OK or NG

OK (With CONSULT)>>GO TO 6.

OK (Without CONSULT)>>GO TO 7.

>> GO TO 5.

DETECT MALFUNCTIONING PART

Check the following.

• Fuel pump and circuit (Refer to

EC-406, "Diagnosis Procedure"

• Fuel pressure regulator (Refer to

EC-487, "Fuel Pressure Check"

• Fuel lines

• Fuel filter for clogging

>> Repair or replace.

CHECK MASS AIR FLOW SENSOR

With CONSULT

1. Install all removed parts.

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

OK or NG

>> GO TO 8.

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

ground. Refer to

EC-118, "Component Description"

CHECK MASS AIR FLOW SENSOR

With GST

1. Install all removed parts.

2. Check mass air flow sensor signal in Service $01 with GST.

OK or NG

OK (P0171)>>GO TO 9.

OK (P0174)>>GO TO 11.

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

ground. Refer to

EC-118, "Component Description"

CHECK FUNCTION OF FUEL INJECTOR

With CONSULT

1. Start engine.

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

3. Make sure that each circuit produces a momentary engine speed drop.

At idling: 350 kPa (3.57 kg/cm

, 51 psi)

2.0 - 6.0 g/s:

at idling

7.0 - 20.0 g/s:

at 2,500 rpm

2.0 - 6.0 g/s:

at idling

7.0 - 20.0 g/s:

at 2,500 rpm

August 2012

2012 Pathfinder

P0171, P0174 FUEL INJECTION SYSTEM FUNCTION

EC-189

< DTC/CIRCUIT DIAGNOSIS >

[VQ40DE]

OK or NG

>> GO TO 12.

>> Perform trouble diagnosis for FUEL INJECTOR, refer to

CHECK FUNCTION OF FUEL INJECTOR-I

Without CONSULT

1. Stop engine.

2. Disconnect harness connector F44 (3), F201 (1)

3. Turn ignition switch ON.

4. Check voltage between harness connector F44 terminal 3 and

ground with CONSULT or tester.

5. Turn ignition switch OFF.

6. Disconnect ECM harness connector.

7. Check harness continuity between harness connector F44 and

ECM as follows.

Refer to Wiring Diagram.

8. Also check harness for short to ground and short to power.
OK or NG

>> GO TO 10.

>> Perform trouble diagnosis for FUEL INJECTOR, refer to

10.

CHECK FUNCTION OF FUEL INJECTOR-II

Provide battery voltage between harness connector F201 as follows

and then interrupt it. Listen to each fuel injector operating sound.

OK or NG

: Vacuum tank

: Front

AWBIA0686ZZ

Voltage: Battery voltage

Cylinder

Harness connector F44

terminal

ECM terminal

Continuity should exist.

PBIB2633E

Cylinder

Harness connector F201 terminal

(+)

(–)

Operating sound should exist.

PBIB2634E

August 2012

2012 Pathfinder

EC-190

< DTC/CIRCUIT DIAGNOSIS >

[VQ40DE]

P0171, P0174 FUEL INJECTION SYSTEM FUNCTION

>> GO TO 12.

>> Perform trouble diagnosis for FUEL INJECTOR, refer to

11.

CHECK FUNCTION OF FUEL INJECTOR

1. Start engine.

2. Listen to fuel injectors No.2, No.4, No.6 operating sound.

OK or NG

>> GO TO 12.

>> Perform trouble diagnosis for FUEL INJECTOR, refer to

EM-47, "Removal and Installation"

12.

CHECK FUEL INJECTOR

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

2. Turn ignition switch OFF.

3. Disconnect all injector harness connectors.

4. Remove fuel tube assembly. Refer to

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

5. For DTC P0171, reconnect fuel injector harness connectors on bank 1.

For DTC P0174, reconnect fuel injector harness connectors on bank 2.

6. Disconnect all ignition coil harness connectors.

7. Prepare pans or saucers under each fuel injector.

8. Crank engine for about 3 seconds.

For DTC P0171, make sure that fuel sprays out from fuel injec-

tors on bank 1.

For DTC P0174, make sure that fuel sprays out from fuel injec-

tors on bank 2.

OK or NG

>> GO TO 13.

>> Replace fuel injectors from which fuel does not spray

out. Refer to

EM-47, "Removal and Installation"

. Always

replace O-ring with new ones.

13.

CHECK INTERMITTENT INCIDENT

Refer to

GI-37, "Intermittent Incident"

INSPECTION END

Clicking noise should exist.

PBIB1986E

Fuel should be sprayed evenly for each fuel injector.

PBIB1726E

August 2012

2012 Pathfinder

P0172, P0175 FUEL INJECTION SYSTEM FUNCTION

EC-191

< DTC/CIRCUIT DIAGNOSIS >

[VQ40DE]

P0172, P0175 FUEL INJECTION SYSTEM FUNCTION

On Board Diagnosis Logic

INFOID:0000000007358104

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 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 rich), the ECM

judges the condition as the fuel injection system malfunction and illuminates the MIL (2 trip detection logic).

DTC Confirmation Procedure

INFOID:0000000007358105

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

SULT.

4. Clear the self-learning control coefficient by touching “CLEAR”.
5. Start engine.

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

Performing the following procedure is advised.

a. 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.

b. If engine starts, go to

If engine does not start, remove ignition plugs and check for fouling, etc. Refer to

EM-42, "Removal and

Installation"

6. Keep engine at idle for at least 5 minutes.
7. Check 1st trip DTC.
8. The 1st trip DTC P0172 or P0175 should be detected at this stage, if a malfunction exists. If so, go to

192, "Diagnosis Procedure"

NOTE:

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

a. Turn ignition switch OFF and wait at least 10 seconds.
b. Start engine.
c. Maintain the following conditions for at least 10 consecutive minutes.

Hold the accelerator pedal as steady as possible.

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

P0172
0172
(Bank 1)

Fuel injection system
too rich

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

large. (The mixture ratio is too rich.)

• Air fuel ratio (A/F) sensor 1
• Fuel injector
• Exhaust gas leaks
• Incorrect fuel pressure
• Mass air flow sensor

P0175
0175
(Bank 2)

August 2012

2012 Pathfinder

EC-192

< DTC/CIRCUIT DIAGNOSIS >

[VQ40DE]

P0172, P0175 FUEL INJECTION SYSTEM FUNCTION

CAUTION:

Always drive vehicle at a safe speed.

d. Check 1st trip DTC.
e. If 1st trip DTC is detected, go to

WITH GST

nector.

6. Select Service $03 with GST. Check that DTC P0102 is

detected.

7. Select Service $04 with GST and erase the DTC P0102.
8. Start engine.

If it is difficult to start engine, the fuel injection system has a mal-

function.

Performing the following procedure is advised.

a. 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.

b. If engine starts, go to

If engine does not start, remove ignition plugs and check for fouling, etc. Refer to

EM-42, "Removal and

Installation"

9. Keep engine at idle for at least 5 minutes.
10. Check 1st trip DTC.
11. The 1st trip DTC P0172 or P0175 should be detected at this stage, if a malfunction exists. If so, go to

192, "Diagnosis Procedure"

NOTE:

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

a. Turn ignition switch OFF and wait at least 10 seconds.
b. Start engine.
c.

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.

d. Check 1st trip DTC.
e. If 1st trip DTC is detected, go to