Nissan X-Trail 32. Manual — part 882
P0172 FUEL INJECTION SYSTEM FUNCTION
EC-657
< DTC/CIRCUIT DIAGNOSIS >
[QR25DE]
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P0172 FUEL INJECTION SYSTEM FUNCTION
DTC Description
INFOID:0000000010986353
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 rich.), the
ECM judges the condition as the fuel injection system malfunction and lights up the MIL (2 trip detection logic).
POSSIBLE CAUSE
• A/F sensor 1
• Fuel injector
• Exhaust gas leaks
• Incorrect fuel pressure
• Mass air flow sensor
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
.
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?
YES
>> Proceed to
.
NO
>> Check exhaust and intake air leak visually.
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
P0172
FUEL SYS-RICH-B1
(System too rich bank 1)
• Fuel injection system does not operate properly.
• The amount of mixture ratio compensation is too large. (The mixture ratio
is too rich.)
EC-658
< DTC/CIRCUIT DIAGNOSIS >
[QR25DE]
P0172 FUEL INJECTION SYSTEM FUNCTION
4.
PERFORM DTC CONFIRMATION PROCEDURE-2
1.
Start engine and let it idle for at least 5 minutes.
2.
Check 1st trip DTC.
Is 1st trip DTC detected?
YES
>> Proceed to
.
NO
>> GO TO 5.
5.
PERFORM DTC CONFIRMATION PROCEDURE-3
1.
Turn ignition switch OFF and wait at least 10 seconds.
2.
Start engine.
3.
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.
4.
Check 1st trip DTC.
Is 1st trip DTC detected?
YES
>> Proceed to
.
NO
>> INSPECTION END
Diagnosis Procedure
INFOID:0000000010986354
1.
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 error-detected parts.
NO
>> GO TO 2.
2.
CHECK FOR INTAKE AIR LEAK
1.
Listen for an intake air leak after the mass air flow sensor.
2.
Check PCV hose connection.
Intake air leak detected?
YES
>> Repair or replace error-detected parts.
NO
>> GO TO 3.
3.
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 the continuity between A/F sensor 1 harness connector and ECM harness connector.
VHCL SPEED SE
50 - 120 km/h (31 - 75 MPH)
PBIB1216E
P0172 FUEL INJECTION SYSTEM FUNCTION
EC-659
< DTC/CIRCUIT DIAGNOSIS >
[QR25DE]
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5.
Check the continuity between A/F sensor 1 harness connector and ground, or ECM harness connector
and ground.
6.
Also check harness for short to power.
Is the inspection result normal?
YES
>> GO TO 4.
NO
>> Repair or replace error-detected parts.
4.
CHECK FUEL PRESSURE
Check fuel pressure. Refer to
Is the inspection result normal?
YES
>> GO TO 6.
NO
>> GO TO 5.
5.
DETECT MALFUNCTIONING PART
Check fuel hoses and fuel tubes for clogging. Refer to
.
Is the inspection result normal?
YES
>> Replace “fuel filter and fuel pump assembly”. Refer to
FL-12, "Removal and Installation"
.
NO
>> Repair or replace error-detected parts.
6.
CHECK MASS AIR FLOW SENSOR
With CONSULT
1.
Install all removed parts.
2.
Start engine and warm it up to normal operating temperature.
3.
Check “MASS AIR FLOW SENSOR (Hz)” in “DATA MONITOR” mode of “ENGINE” using CONSULT.
*: Check for linear frequency rise in response to engine being increased to about 4,000 rpm.
+
−
Continuity
A/F sensor 1
ECM
Connector
Terminal
Connector
Terminal
F27
1
F85
41
Existed
2
45
+
−
Continuity
A/F sensor 1
Connector
Terminal
F27
1
Ground
Not existed
2
+
−
Continuity
ECM
Connector
Terminal
F85
41
Ground
Not existed
45
Monitor item
Condition
Value
MASS AIR
FLOW SENSOR
(Hz)
Ignition switch ON (Engine stopped.)
Approx. 3500 Hz
Idle (Engine is warmed-up to normal operating temper-
ature.)
3500- 4100 Hz
2,500 rpm (Engine is warmed-up to normal operating
temperature.)
5000k - 5600 Hz
Idle to about 4,000 rpm
3500 - 4100 Hz to Approx. 6300 Hz*
EC-660
< DTC/CIRCUIT DIAGNOSIS >
[QR25DE]
P0172 FUEL INJECTION SYSTEM FUNCTION
Without CONSULT
1.
Install all removed parts.
2.
Start engine and warm it up to normal operating temperature.
3.
Check mass air flow sensor signal in Service $01 with GST.
*: Check for linear frequency rise in response to engine being increased to about 4,000 rpm.
Is the measurement value within the specification?
YES
>> GO TO 7.
NO
>> Check connectors for rusted terminals or loose connections in the mass air flow sensor circuit or
grounds. Refer to
7.
CHECK FUNCTION OF FUEL INJECTOR
With CONSULT
1.
Start engine.
2.
Perform “POWER BALANCE” in “ACTIVE TEST” mode of “ENGINE” using CONSULT.
3.
Make sure that each circuit produces a momentary engine speed drop.
Without CONSULT
1.
Let engine idle.
2.
Listen to each fuel injector operating sound.
Is the inspection result normal?
YES
>> GO TO 8.
NO
>> Perform trouble diagnosis for “FUEL INJECTOR”, refer
to
EC-779, "Component Function Check"
.
8.
CHECK FUEL INJECTOR
1.
Turn ignition switch OFF.
2.
Confirm that the engine is cooled down and there are no fire hazards near the vehicle.
3.
Disconnect all fuel injector harness connectors.
4.
Remove fuel tube assembly. Refer to
EM-184, "Removal and Installation"
.
Keep fuel hose and all fuel injectors connected to fuel tube.
5.
Disconnect all ignition coil harness connectors.
6.
Prepare pans or saucers under each fuel injector.
ECM
Condition
Value
Connector
+
−
Terminal
F85
35
34
Ignition switch ON (Engine stopped.)
Approx. 3500 Hz
Idle (Engine is warmed-up to normal operating temper-
ature.)
3500- 4100 Hz
2,500 rpm (Engine is warmed-up to normal operating
temperature.)
5000k - 5600 Hz
Idle to about 4,000 rpm
3500 - 4100 Hz to Approx. 6300 Hz*
Ignition switch ON (Engine stopped.)
Approx. 3500 Hz
Clicking noise should be heard.
PBIB3332E
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