Nissan Frontier. Instruction — part 414
P014C, P014D, P015A, P015B, A/F SENSOR 1
EC-227
< DTC/CIRCUIT DIAGNOSIS >
[QR25DE]
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4. Check the continuity between A/F sensor 1 harness connector or ECM harness connector and ground.
5. Also check harness for short to power.
Is the inspection result normal?
YES
>> GO TO 9.
NO
>> Repair open circuit or short to ground or short to power in harness or connectors.
9.
CHECK AIR FUEL RATIO (A/F) SENSOR 1 HEATER
Check A/F sensor 1 heater. Refer to
EC-157, "Component Inspection"
.
Is the inspection result normal?
YES
>> GO TO 10.
NO
>> GO TO 13.
10.
CHECK MASS AIR FLOW SENSOR
Check mass air flow sensor. Refer to
EC-170, "Component Inspection"
Is the inspection result normal?
YES
>> GO TO 11.
NO
>> Replace mass air flow sensor. Refer to
EM-27, "Removal and Installation"
.
11.
CHECK PCV VALVE
Check PCV valve. Refer to
EC-456, "Component Inspection"
.
Is the inspection result normal?
YES
>> GO TO 12.
NO
>> Repair or replace PCV valve. Refer to
12.
CHECK INTERMITTENT INCIDENT
Perform intermittent incident. Refer to
GI-42, "Intermittent Incident"
.
Is the inspection result normal?
YES
>> GO TO 13.
NO
>> Repair or replace.
13.
REPLACE AIR FUEL RATIO (A/F) SENSOR 1
Replace air fuel ratio (A/F) sensor 1. Refer to
EM-31, "Removal and Installation"
CAUTION:
• Discard any sensor which has been dropped from a height of more than 0.5 m (19.7 in) onto a hard
surface such as a concrete floor; use a new one.
• Before installing new sensor, clean exhaust system threads using oxygen sensor thread cleaner
[commercial service tool (J-43897-18 or J-43897-12)] and approved anti-seize lubricant (commercial
service tool).
>> INSPECTION END
A/F sensor 1
ECM
Continuity
Connector
Terminal
Connector
Terminal
F65
1
F56
45
Existed
2
49
A/F sensor 1
ECM
Ground
Continuity
Connector
Terminal
Connector
Terminal
F65
1
F56
45
Ground
Not existed
2
49
EC-228
< DTC/CIRCUIT DIAGNOSIS >
[QR25DE]
P0171 FUEL INJECTION SYSTEM FUNCTION
P0171 FUEL INJECTION SYSTEM FUNCTION
On Board Diagnosis Logic
INFOID:0000000009480886
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 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 illuminates the MIL (2 trip detection
logic).
DTC Confirmation Procedure
INFOID:0000000009480887
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
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.
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, 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 should be detected at this stage, if a malfunction exists. If so, go to
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
Air fuel ratio (A/F) sensor 1
Density of oxygen in exhaust gas
(Mixture ratio feedback signal)
Fuel injec-
tion control
Fuel injector
DTC No.
Trouble diagnosis
name
DTC detecting condition
Possible cause
P0171
0171
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
P0171 FUEL INJECTION SYSTEM FUNCTION
EC-229
< DTC/CIRCUIT DIAGNOSIS >
[QR25DE]
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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 should be detected at this stage, if a malfunction exists. If so, go to
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
Diagnosis Procedure
INFOID:0000000009480888
1.
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)
BBIA0622E
EC-230
< DTC/CIRCUIT DIAGNOSIS >
[QR25DE]
P0171 FUEL INJECTION SYSTEM FUNCTION
2. Listen for an exhaust gas leak before three way catalyst (manifold).
OK or NG
OK
>> GO TO 2.
NG
>> Repair or replace.
2.
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
OK
>> GO TO 3.
NG
>> Repair or replace.
3.
CHECK AIR FUEL RATIO (A/F) SENSOR 1 CIRCUIT FOR OPEN AND SHORT
1. Turn ignition switch OFF.
2. Disconnect A/F sensor 1 harness connector and ECM harness
connector.
3. Check harness continuity between ECM terminals and A/F sen-
sor 1 terminals as follows.
Refer to Wiring Diagram.
4. Check harness continuity between ECM terminals 45, 49 and ground, or A/F sensor 1 terminals 1, 2 and
ground.
Refer to Wiring Diagram.
5. Also check harness for short to power.
OK or NG
OK
>> GO TO 4.
NG
>> Repair open circuit, short to ground or short to power in harness or connectors.
4.
CHECK FUEL PRESSURE
1. Release fuel pressure to zero. Refer to
2. Install fuel pressure gauge kit [SST (J-44321)] and check fuel pressure. Refer to
.
OK or NG
OK
>> GO TO 6.
NG
>> GO TO 5.
5.
DETECT MALFUNCTIONING PART
PBIB1216E
A/F sensor 1
ECM terminal
1
45
2
49
Continuity should exist.
Continuity should not exist.
BBIA0617E
At idling: Approximately 350 kPa (3.57 kg/cm
2
, 51 psi)
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