Nissan Frontier. Manual - part 533

P0171, P0174 FUEL INJECTION SYSTEM FUNCTION

EC-703

< DTC/CIRCUIT DIAGNOSIS >

[VQ40DE FOR USA AND CANADA]

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

OK

>> GO TO 4.

NG

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

4.

CHECK FUEL PRESSURE

1. Release fuel pressure to zero. Refer to 

EC-959, "Fuel Pressure Check"

.

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

EC-959, "Fuel Pressure Check"

.

OK or NG

OK (With CONSULT)>>GO TO 6.

OK (Without CONSULT)>>GO TO 7.

NG

>> GO TO 5.

5.

DETECT MALFUNCTIONING PART

Check the following.

• Fuel pump and circuit (Refer to 

EC-932, "Description"

.)

• Fuel pressure regulator (Refer to 

EC-959, "Fuel Pressure Check"

.)

• Fuel lines

• Fuel filter for clogging

>> Repair or replace.

6.

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

OK

>> GO TO 8.

NG

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

ground. Refer to 

EC-633, "Component Description"

.

7.

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.

NG

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

ground. Refer to 

EC-633, "Component Description"

.

8.

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.

At idling: 350 kPa (3.57 kg/cm

2

, 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

EC-704

< DTC/CIRCUIT DIAGNOSIS >

[VQ40DE FOR USA AND CANADA]

P0171, P0174 FUEL INJECTION SYSTEM FUNCTION

OK or NG

OK

>> GO TO 12.

NG

>> Perform trouble diagnosis for FUEL INJECTOR, refer to 

EC-928, "Component Description"

.

9.

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

OK

>> GO TO 10.

NG

>> Perform trouble diagnosis for FUEL INJECTOR, refer to 

EC-928, "Component Description"

.

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

OK

>> GO TO 12.

NG

>> Perform trouble diagnosis for FUEL INJECTOR, refer to 

EC-928, "Component Description"

.

2

: Vacuum tank

: Front

AWBIA0686ZZ

Voltage: Battery voltage

Cylinder

Harness connector F44 

terminal

ECM terminal

1

2

33

3

1

48

5

4

46

Continuity should exist.

Cylinder

Harness connector F201 terminal

(+)

(–)

1

3

2

3

3

1

5

3

4

Operating sound should exist.

P0171, P0174 FUEL INJECTION SYSTEM FUNCTION

EC-705

< DTC/CIRCUIT DIAGNOSIS >

[VQ40DE FOR USA AND CANADA]

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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

OK

>> GO TO 12.

NG

>> Perform trouble diagnosis for FUEL INJECTOR, refer to

EC-928, "Component Description"

.

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 

EM-162, "Removal and Installation"

.

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, check that fuel sprays out from fuel injectors on

bank 1.

For DTC P0174, check that fuel sprays out from fuel injectors on

bank 2.

OK or NG

OK

>> GO TO 13.

NG

>> Replace fuel injectors from which fuel does not spray

out. Always replace O-ring with new ones. Refer to 

EM-

162, "Exploded View"

.

13.

CHECK INTERMITTENT INCIDENT

Refer to 

GI-42, "Intermittent Incident"

.

>> INSPECTION END

Clicking noise should exist.

PBIB1986E

Fuel should be sprayed evenly for each fuel injector.

PBIB1726E

EC-706

< DTC/CIRCUIT DIAGNOSIS >

[VQ40DE FOR USA AND CANADA]

P0172, P0175 FUEL INJECTION SYSTEM FUNCTION

P0172, P0175 FUEL INJECTION SYSTEM FUNCTION

On Board Diagnosis Logic

INFOID:0000000009481360

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 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:0000000009481361

NOTE:

If DTC Confirmation Procedure has been previously conducted, always perform the following before conduct-

ing the next step. 
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.

 WITH CONSULT

1. Start engine and warm it up to normal operating temperature.
2. Turn ignition switch OFF and wait at least 10 seconds.
3. Turn ignition switch ON and select “SELF-LEARNING CONT” in “WORK SUPPORT” mode with CON-

SULT.

4. Clear the self-learning control coefficient by touching “CLEAR”.
5. Start engine again and let it idle for at least 10 minutes.
6. Check 1st trip DTC.

The 1st trip DTC P0172, P0175 should be detected at this stage, if a malfunction exists. If so, go to 

EC-

707, "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 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.

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)

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)