Content .. 234 235 236 237 ..

Nissan Titan. Manual - part 236

P0172, P0175 FUEL INJECTION SYSTEM FUNCTION

EC-245

< DTC/CIRCUIT DIAGNOSIS >

[VK56DE]

P0172, P0175 FUEL INJECTION SYSTEM FUNCTION

On Board Diagnosis Logic

INFOID:0000000009886652

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 rich.), the

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

DTC Confirmation Procedure

INFOID:0000000009886653

NOTE:

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

ing the next step.
1. Turn ignition swich OFF and wait at least 10 seconds.
2. Turn ignition swich ON.
3. Turn ignition swich 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-

246, "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.)

• 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)

EC-246

< DTC/CIRCUIT DIAGNOSIS >

[VK56DE]

P0172, P0175 FUEL INJECTION SYSTEM FUNCTION

7. If it is difficult to start engine at step 6, the fuel injection system has a malfunction, too.
8. Crank engine while depressing accelerator pedal.

If engine starts, go to

EC-246, "Diagnosis Procedure"

. If engine does not start, remove spark plugs and

check for fouling, etc.

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. Then

restart and run engine for at least 5 seconds at idle speed.

4. Stop engine and reconnect mass air flow sensor harness con-

nector.

5. Select Service $03 with GST. Make sure DTC P0102 is

detected.

6. Select Service $04 with GST and erase the DTC P0102.
7. Start engine again and let it idle for at least 10 minutes.
8. Select Service $07 with GST. The 1st trip DTC P0172 or P0175

should be detected at this stage, if a malfunction exists. If so, go

EC-246, "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.

9. If it is difficult to start engine at step 7, the fuel injection system has a malfunction.
10. Crank engine while depressing accelerator pedal.

If engine starts, go to

EC-246, "Diagnosis Procedure"

. If engine does not start, remove spark plugs and

check for fouling, etc.

Diagnosis Procedure

INFOID:0000000009886654

CHECK EXHAUST GAS LEAK

1. Start engine and run it at idle.

Engine coolant temperature (T)
condition

When the freeze frame data shows lower than 70

°C (158 °F),

T should be lower than 70

°C (158 °F).

When the freeze frame data shows higher than or equal to 70

°C (158 °F),

T should be higher than or equal to 70

°C (158 °F).

BBIA0368E

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)

Engine coolant temperature (T)
condition

When the freeze frame data shows lower than 70

°C (158 °F),

T should be lower than 70

°C (158 °F).

When the freeze frame data shows higher than or equal to 70

°C (158 °F),

T should be higher than or equal to 70

°C (158 °F).

P0172, P0175 FUEL INJECTION SYSTEM FUNCTION

EC-247

< DTC/CIRCUIT DIAGNOSIS >

[VK56DE]

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

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

Refer to Wiring Diagram.

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

Refer to Wiring Diagram.

6. Also check harness for short to power.

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.

BBIA0376E

EC-248

< DTC/CIRCUIT DIAGNOSIS >

[VK56DE]

P0172, P0175 FUEL INJECTION SYSTEM FUNCTION

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

EC-489, "Fuel Pressure Check"

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

EC-489, "Fuel Pressure Check"

OK or NG

>> GO TO 6.

>> GO TO 5.

DETECT MALFUNCTIONING PART

Check the following.

• Fuel pump and circuit (Refer to

EC-462

• <Flexible Fuel Vehicle>

FPCM and circuit (Refer to

EC-381

• Fuel pressure regulator (Refer to

EC-489, "Fuel Pressure Check"

>> 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.

With GST

1. Install all removed parts.

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

OK or NG

>> GO TO 7.

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

grounds. Refer to

EC-172

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.

Without CONSULT

1. Start engine.

At idling: Approximately 350 kPa (3.57 kg/cm

, 51 psi)

3.0 - 9.0 g/s

: at idling

9.0 - 28.0 g/s

: at 2,500 rpm

3.0 - 9.0 g/s

: at idling

9.0 - 28.0 g/s

: at 2,500 rpm

Content .. 234 235 236 237 ..