Infiniti FX35 / FX45. Manual - part 525
DTC P0171, P0174 FUEL INJECTION SYSTEM FUNCTION
EC-861
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DTC P0171, P0174 FUEL INJECTION SYSTEM FUNCTION
On Board Diagnosis Logic
INFOID:0000000001326698
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 lean.), the
ECM judges the condition as the fuel injection system malfunction and lights up the MIL (2 trip detection logic).
DTC Confirmation Procedure
INFOID:0000000001326699
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-III
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-III.
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.
Perform the following procedure is advised.
a.
Crank engine while depressing accelerator pedal.
b.
If engine starts, go to
.
If engine does not start, check exhaust and intake air leak visually.
6.
Keep engine at idle for at least 10 minutes.
7.
Check 1st trip DTC.
8.
If 1st trip DTC is detected, go to
If 1st trip DTC is not detected, 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
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
• 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)