2001 NISSAN PICK-UP check engine

8) Select ªMODE 7º with GST. The 1st trip DTC P0171 should be
detected at this stage, if a malfunction exists. If so, go to
ªDiagnostic Procedureº, EC-3240.
9) If it is difficult to start engine at step 8, the fuel injection sys-
tem has a malfunction.
10) Crank engine while depressing accelerator pedal. If engine
starts, go to ªDiagnostic Procedureº, EC-3240. If engine does
not start, visually check for exhaust and intake air leak.
DTC P0171 FUEL INJECTION SYSTEM
FUNCTION
KA24DE (EURO OBD)
DTC Confirmation Procedure
EC-3238

Diagnostic ProcedureNEEC0191
1 CHECK EXHAUST AIR LEAK
1. Start engine and run it at idle.
2. Listen for an exhaust air leak before three way catalyst.
SEF099P
OK or NG
OK©GO TO 2.
NG©Repair or replace.
2 CHECK FOR INTAKE AIR LEAK AND PCV HOSE
1. Listen for an intake air leak between the mass air flow sensor and the intake manifold.
2. Check PCV hose connection.
OK or NG
OK©GO TO 3.
NG©Repair or replace.
3 CHECK HEATED OXYGEN SENSOR 1 CIRCUIT
1. Turn ignition switch OFF.
2. Disconnect heated oxygen sensor 1 harness connector and ECM harness connector.
SEF331VC
3. Check harness continuity between ECM terminal 50 and terminal 2. Refer to wiring diagram.
Continuity should exist.
4. Check harness continuity between ECM terminal 50 (or terminal 2) and ground. Refer to wiring diagram.
Continuity should not exist.
5. Also check harness for short to ground and 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.
DTC P0171 FUEL INJECTION SYSTEM
FUNCTION
KA24DE (EURO OBD)
Diagnostic Procedure
EC-3240

4 CHECK FUEL PRESSURE
1. Release fuel pressure to zero.
Refer to EC-3033.
2. Install fuel pressure gauge and check fuel pressure.
At idling:
When fuel pressure regulator valve vacuum hose is connected.
235 kPa (2.35 bar, 2.4 kg/cm
2, 34 psi)
When fuel pressure regulator valve vacuum hose is disconnected.
294 kPa (2.94 bar, 3.0 kg/cm
2, 43 psi)
OK or NG
OK©GO TO 6.
NG©GO TO 5.
5 DETECT MALFUNCTIONING PART
Check the following.
+Fuel pump and circuit (Refer to EC-3378.)
+Fuel pressure regulator (Refer to EC-3034.)
+Fuel lines (Refer to ªChecking Fuel Linesº, MA section.)
+Fuel filter for clogging
©Repair or replace.
6 CHECK MASS AIR FLOW SENSOR
With CONSULT-II
1. Start engine and warm it up to normal operating temperature.
2. Check ªMASS AIR FLOWº in ªDATA MONITORº mode with CONSULT-II.
at idling: 0.9 - 5.8 g´m/sec
at 2,500 rpm: 7.5 - 13.2 g´m/sec
With GST
1. Start engine and warm it up to normal operating temperature.
2. Check mass air flow sensor signal in MODE 1 with GST.
at idling: 0.9 - 5.8 g´m/sec
at 2,500 rpm: 7.5 - 13.2 g´m/sec
OK or NG
OK©GO TO 7.
NG©Check connectors for rusted terminals or loose connections in the mass air flow sensor
circuit or engine grounds. Refer to EC-3143.
DTC P0171 FUEL INJECTION SYSTEM
FUNCTION
KA24DE (EURO OBD)
Diagnostic Procedure
EC-3241

7 CHECK FUNCTION OF INJECTORS
With CONSULT-II
1. Install all parts removed.
2. Start engine.
3. Perform ªPOWER BALANCEº in ªACTIVE TESTº mode with CONSULT-II.
SEF981Z
4. Make sure that each circuit produces a momentary engine speed drop.
Without CONSULT-II
1. Install all parts removed.
2. Start engine.
3. Listen to each injector operating sound.
MEC703B
Clicking noise should be heard.
OK or NG
OK©GO TO 8.
NG©Perform trouble diagnosis for ªINJECTORSº, EC-3370.
8 REMOVE INJECTOR
1. Confirm that the engine is cooled down and there are no fire hazards near the vehicle.
2. Turn ignition switch OFF.
3. Remove injector with fuel tube assembly. Refer to EC-3034.
Keep fuel hose and all injectors connected to injector gallery. The injector harness connectors should remain con-
nected.
©GO TO 9.
DTC P0171 FUEL INJECTION SYSTEM
FUNCTION
KA24DE (EURO OBD)
Diagnostic Procedure
EC-3242

9 CHECK INJECTOR
1. Disconnect all ignition coil harness connectors.
2. Place pans or saucers under each injector.
3. Crank engine for about 3 seconds. Make sure that fuel sprays out from injectors.
SEF595Q
Fuel should be sprayed evenly for each cylinder.
OK or NG
OK©GO TO 10.
NG©Replace injectors from which fuel does not spray out. Always replace O-ring with new
one.
10 CHECK INTERMITTENT INCIDENT
Perform ªTROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENTº, EC-3123.
©INSPECTION END
DTC P0171 FUEL INJECTION SYSTEM
FUNCTION
KA24DE (EURO OBD)
Diagnostic Procedure
EC-3243

On Board Diagnosis LogicNEEC0192With 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 heated oxygen 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 lights up the MI (2 trip detection logic).
Sensor Input Signal to ECMECM func-
tionActuator
Heated oxygen sensor 1Density of oxygen in exhaust gas
(Mixture ratio feedback signal)Fuel injec-
tion & mix-
ture ratio
controlInjectors
DTC No. Malfunction is detected when ... Check Items (Possible Cause)
P0172
0172+Fuel injection system does not operate properly.
+The amount of mixture ratio compensation is too large.
(The mixture ratio is too rich.)+Heated oxygen sensor 1
+Injectors
+Exhaust gas leaks
+Incorrect fuel pressure
+Mass air flow sensor
SEF215Z
SEF058Y
DTC Confirmation ProcedureNEEC0193NOTE:
If ªDTC Confirmation Procedureº has been previously conducted,
always turn ignition switch OFF and wait at least 5 seconds before
conducting the next test.
With CONSULT-II
1) Start engine and warm it up to normal operating temperature.
2) Turn ignition switch OFF and wait at least 5 seconds.
3) Turn ignition switch ON and select ªSELF-LEARNING CONTº
in ªWORK SUPPORTº mode with CONSULT-II.
4) Clear the self-learning control coefficient by touching ªCLEARº.
5) Select ªDATA MONITORº mode with CONSULT-II.
6) Start engine again and let it idle for at least 10 minutes.
The 1st trip DTC P0172 should be detected at this stage, if a
malfunction exists. If so, go to ªDiagnostic Procedureº,
EC-3247.
7) If it is difficult to start engine at step 6, the fuel injection sys-
tem has a malfunction.
8) Crank engine while depressing accelerator pedal. If engine
starts, go to ªDiagnostic Procedureº, EC-3247. If engine does
not start, remove ignition plugs and check for fouling, etc.
AEC131A
With GST
1) Start engine and warm it up to normal operating temperature.
2) Turn ignition switch OFF and wait at least 5 seconds.
3) Disconnect mass air flow sensor harness connector. Then
restart and run engine for at least 3 seconds at idle speed.
4) Stop engine and reconnect mass air flow sensor harness con-
nector.
5) Select ªMODE 7º with GST. Make sure 1st trip DTC P0102 is
detected.
6) Select ªMODE 4º with GST and erase the 1st trip DTC P0102.
DTC P0172 FUEL INJECTION SYSTEM
FUNCTION
KA24DE (EURO OBD)
On Board Diagnosis Logic
EC-3244

7) Start engine again and run it for at least 10 minutes at idle
speed.
8) Select ªMODE 7º with GST. The 1st trip DTC P0172 should be
detected at this stage, if a malfunction exists. If so, go to
ªDiagnostic Procedureº, EC-3247.
9) If it is difficult to start engine at step 8, the fuel injection sys-
tem has a malfunction.
10) Crank engine while depressing accelerator pedal.
If engine starts, go to ªDiagnostic Procedureº, EC-3247. If
engine does not start, remove ignition plugs and check for
fouling, etc.
DTC P0172 FUEL INJECTION SYSTEM
FUNCTION
KA24DE (EURO OBD)
DTC Confirmation Procedure
EC-3245

Diagnostic ProcedureNEEC0195
1 CHECK FOR EXHAUST AIR LEAK
1. Start engine and run it at idle.
2. Listen for an exhaust air leak before three way catalyst.
SEF099P
OK or NG
OK©GO TO 2.
NG©Repair or replace.
2 CHECK HEATED OXYGEN SENSOR 1 CIRCUIT
1. Turn ignition switch OFF.
2. Disconnect heated oxygen sensor 1 harness connector and ECM harness connector.
SEF331VC
3. Check harness continuity between ECM terminal 50 and terminal 2. Refer to wiring diagram.
Continuity should exist.
4. Check harness continuity between ECM terminal 50 (or terminal 2) and ground. Refer to wiring diagram.
Continuity should not exist.
5. Also check harness for short to ground and short to power.
OK or NG
OK©GO TO 3.
NG©Repair open circuit or short to ground or short to power in harness or connectors.
DTC P0172 FUEL INJECTION SYSTEM
FUNCTION
KA24DE (EURO OBD)
Diagnostic Procedure
EC-3247