2001 INFINITI QX4 Ignition harness

Diagnostic ProcedureNBEC0161
1 INSPECTION START
1. Turn ignition switch ªOFFº.
2. Loosen and retighten engine ground screws.
SEF959Y
3. Check heated oxygen sensor 2 (rear) harness protector color.
SEF372Z
4. Disconnect corresponding heated oxygen sensor 2 (rear) harness connector.
SEF971Y
5. Disconnect ECM harness connector.
©GO TO 2.
DTC P0140, P0160 HEATED OXYGEN SENSOR 2 (REAR) (BANK 1)/(BANK 2)
(HIGH VOLTAGE)
Diagnostic Procedure
EC-282

7 CHECK HEATED OXYGEN SENSOR 2 (REAR)-II
Idle vehicle for 10 minutes, then check voltage between the same terminals as in Test No. 6; or check voltage when coast-
ing from 80 km/h (50 MPH) in ªDº position with ªODº OFF.
The voltage should go below 0.57V at least once during this procedure.
CAUTION:
Discard any heated oxygen 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.
OK or NG
OK©GO TO 9.
NG©GO TO 8.
8 REPLACE HEATED OXYGEN SENSOR 2 (REAR)
1. Stop vehicle and turn ignition switch ªOFFº.
2. Check heated oxygen sensor 2 (rear) harness protector color.
SEF372Z
CAUTION:
Before installing new oxygen sensor, clean exhaust system threads using Oxygen Sensor Thread Cleaner tool
J-43897-18 or J-43897-12 and approved anti-seize lubricant.
©Replace malfunctioning heated oxygen sensor 2 (rear).
9 CHECK INTERMITTENT INCIDENT
Refer to ªTROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENTº, EC-140.
©INSPECTION END
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DTC P0140, P0160 HEATED OXYGEN SENSOR 2 (REAR) (BANK 1)/(BANK 2)
(HIGH VOLTAGE)
Diagnostic Procedure (Cont'd)
EC-285

On Board Diagnosis LogicNBEC0165Malfunction is detected when the current amperage in the heated
oxygen sensor 2 heater (rear) circuit is out of the normal range.
[An improper voltage drop signal is sent to ECM through the heated
oxygen sensor 2 heater (rear).]
Possible CauseNBEC0442IHarness or connectors
[The heated oxygen sensor 2 heater (rear) circuit is open or
shorted.]
IHeated oxygen sensor 2 heater (rear)
SEF058Y
DTC Confirmation ProcedureNBEC0166NOTE:
If ªDTC Confirmation Procedureº has been previously conducted,
always turn ignition switch ªOFFº and wait at least 10 seconds
before conducting the next test.
TESTING CONDITION:
Before performing the following procedure, confirm that bat-
tery voltage is between 10.5V and 16V at idle.
WITH CONSULT-IINBEC0166S011) Turn ignition switch ªONº and select ªDATA MONITORº mode
with CONSULT-II.
2) Start engine.
3) Drive vehicle at a speed of more than 70 km/h (43 MPH) for 2
consecutive minutes.
4) Stop vehicle and let engine idle for at least 6 seconds.
5) If 1st trip DTC is detected, go to ªDiagnostic Procedureº,
EC-291.
WITH GSTNBEC0166S021) Start engine.
2) Drive vehicle at a speed of more than 70 km/h (43 MPH) for 2
consecutive minutes.
3) Stop vehicle and let engine idle for at least 6 seconds.
4) Turn ignition switch ªOFFº and wait at least 10 seconds.
5) Start engine.
6) Drive vehicle at a speed of more than 70 km/h (43 MPH) for 2
consecutive minutes.
7) Stop vehicle and let engine idle for at least 6 seconds.
8) Select ªMODE 3º with GST.
9) If DTC is detected, go to ªDiagnostic Procedureº, EC-291.
IWhen using GST, ªDTC Confirmation Procedureº should
be performed twice as much as when using CONSULT-II
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DTC P0141, P0161 HEATED OXYGEN SENSOR 2 HEATER (REAR) (BANK 1)/
(BANK 2)
On Board Diagnosis Logic
EC-287

Diagnostic ProcedureNBEC0168
1 CHECK HO2S2 (REAR) POWER SUPPLY CIRCUIT
1. Turn ignition switch ªOFFº.
2. Check heated oxygen sensor harness 2 (rear) protector color.
SEF372Z
3. Disconnect corresponding heated oxygen sensor 2 (rear) harness connector.
SEF971Y
4. Turn ignition switch ªONº.
5. Check voltage between HO2S2 terminal 3 and ground.
SEF314X
OK or NG
OK©GO TO 3.
NG©GO TO 2.
2 DETECT MALFUNCTIONING PART
Check the following.
IHarness connectors M32, F23
IFuse block (J/B) connector M10
I15A fuse
IHarness for open or short between heated oxygen sensor 2 (rear) and fuse
©Repair harness or connectors.
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DTC P0141, P0161 HEATED OXYGEN SENSOR 2 HEATER (REAR) (BANK 1)/
(BANK 2)
Diagnostic Procedure
EC-291

3 CHECK HO2S2 (REAR) OUTPUT CIRCUIT FOR OPEN AND SHORT
1. Turn ignition switch ªOFFº.
2. Disconnect ECM harness connector.
3. Check harness continuity between ECM terminal and HO2S2 terminal as follows.
Refer to Wiring Diagram.
MTBL0529
Continuity should exist.
4. 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.
4 CHECK HEATED OXYGEN SENSOR 2 HEATER (REAR)
Check the resistance between HO2S2 terminals as follows.
SEF315X
CAUTION:
Discard any heated oxygen 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.
OK or NG
OK©GO TO 6.
NG©GO TO 5.
5 REPLACE HEATED OXYGEN SENSOR 2 (REAR)
Check heated oxygen sensor 2 harness (rear) protector color.
SEF372Z
CAUTION:
Before installing new oxygen sensor, clean exhaust system threads using Oxygen Sensor Thread Cleaner tool
J-43897-18 or J-43897-12 and approved anti-seize lubricant.
©Replace malfunctioning heated oxygen sensor 2 (rear).
DTC P0141, P0161 HEATED OXYGEN SENSOR 2 HEATER (REAR) (BANK 1)/
(BANK 2)
Diagnostic Procedure (Cont'd)
EC-292

SEF960Y
WITH GSTNBEC0170S021) Start engine and warm it up to normal operating temperature.
2) Turn ignition switch ªOFFº 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 ªMODE 7º with GST. Make sure 1st trip DTC P0100 is
detected.
6) Select ªMODE 4º with GST and erase the 1st trip DTC P0100.
7) Start engine again and let it idle for at least 10 minutes.
8) Select ªMODE 7º with GST. The 1st trip DTC P0171 or P0174
should be detected at this stage, if a malfunction exists. If so,
go to ªDiagnostic Procedureº, EC-298.
9) If it is difficult to start engine at step 7, the fuel injection sys-
tem has a malfunction.
10) Crank engine while depressing accelerator pedal. If engine
starts, go to ªDiagnostic Procedureº, EC-298. If engine does
not start, check exhaust and intake air leak visually.
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DTC P0171 (RIGHT, -B1), P0174 (LEFT, -B2) FUEL INJECTION SYSTEM
FUNCTION (LEAN)
DTC Confirmation Procedure (Cont'd)
EC-295

Diagnostic ProcedureNBEC0172
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
Listen for an intake air leak after the mass air flow sensor.
OK or NG
OK©GO TO 3.
NG©Repair or replace.
3 CHECK HEATED OXYGEN SENSOR 1 (FRONT) CIRCUIT FOR OPEN AND SHORT
1. Turn ignition switch ªOFFº.
2. Disconnect corresponding heated oxygen sensor 1 (front) harness connector.
3. Disconnect ECM harness connector.
4. Check harness continuity between ECM terminal and HO2S1 terminal as follows.
Refer to Wiring Diagram.
MTBL0477
Continuity should exist.
5. Check harness continuity between ECM terminal or HO2S1 terminal and ground as follows.
Refer to Wiring Diagram.
MTBL0478
Continuity should not exist.
6. Also check harness for 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 (RIGHT, -B1), P0174 (LEFT, -B2) FUEL INJECTION SYSTEM
FUNCTION (LEAN)
Diagnostic Procedure
EC-298

8 CHECK INJECTOR
1. Confirm that the engine is cooled down and there are no fire hazards near the vehicle.
2. Turn ignition switch ªOFFº.
3. Disconnect injector harness connectors on left bank (for DTC P0171), right bank (for DTC P0174).
4. Remove injector gallery assembly. Refer to EC-41.
Keep fuel hose and all injectors connected to injector gallery.
The injector harness connectors on right bank (for DTC P0171), left bank (for DTC P0174) should remain connected.
5. Disconnect all ignition coil harness connectors.
6. Prepare pans or saucers under each injector.
7. Crank engine for about 3 seconds. Make sure that fuel sprays out from injectors.
SEF595Q
Fuel should be sprayed evenly for each injector.
OK or NG
OK©GO TO 9.
NG©Replace injectors from which fuel does not spray out. Always replace O-ring with new
ones.
9 CHECK INTERMITTENT INCIDENT
Refer to ªTROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENTº, EC-140.
©INSPECTION END
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DTC P0171 (RIGHT, -B1), P0174 (LEFT, -B2) FUEL INJECTION SYSTEM
FUNCTION (LEAN)
Diagnostic Procedure (Cont'd)
EC-301