Infiniti QX4 (R50). Manual — part 201

LEFT BANK

NBEC0152S02

MEC952C

GI

MA

EM

LC

FE

AT

TF

PD

AX

SU

BR

ST

RS

BT

HA

SC

EL

IDX

DTC P0139, P0159 HEATED OXYGEN SENSOR 2 (REAR) (BANK 1)/(BANK 2)

(RESPONSE MONITORING)

Wiring Diagram (Cont’d)

EC-271

Diagnostic Procedure

NBEC0153

1

RETIGHTEN GROUND SCREWS

1. Turn ignition switch “OFF”.
2. Loosen and retighten engine ground screws.

SEF959Y

©

GO TO 2.

2

CLEAR THE SELF-LEARNING DATA

With CONSULT-II

1. Start engine and warm it up to normal operating temperature.
2. Select “SELF-LEARNING CONT” in “WORK SUPPORT” mode with CONSULT-II.
3. Clear the self-learning control coefficient by touching “CLEAR”.

SEF968Y

4. Run engine for at least 10 minutes at idle speed.

Is the 1st trip DTC P0171, P0172, P0174 or P0175 detected?
Is it difficult to start engine?

Without CONSULT-II

1. Start engine and warm it up to normal operating temperature.
2. Turn ignition switch “OFF”.
3. Disconnect mass air flow sensor harness connector, and restart and run engine for at least 5 seconds at idle speed.
4. Stop engine and reconnect mass air flow sensor harness connector.
5. Make sure 1st trip DTC No. 0100 is displayed.
6. Erase the 1st trip DTC memory. Refer to “HOW TO ERASE EMISSION-RELATED DIAGNOSTIC INFORMATION”,

EC-72.

7. Make sure DTC No. 0000 is displayed.
8. Run engine for at least 10 minutes at idle speed.

Is the 1st trip DTC P0171, P0172, P0174 or P0175 detected?
Is it difficult to start engine?

Yes or No

Yes

©

Perform trouble diagnosis for DTC P0171, P0174 or P0172, P0175. Refer to EC-294,
302.

No

©

GO TO 3.

DTC P0139, P0159 HEATED OXYGEN SENSOR 2 (REAR) (BANK 1)/(BANK 2)

(RESPONSE MONITORING)

Diagnostic Procedure

EC-272

3

CHECK HO2S2 (REAR) INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT

1. Turn ignition switch “OFF”.
2. Check heated oxygen sensor 2 (rear) harness protector color.

SEF372Z

3. Disconnect corresponding heated oxygen sensor 2 (rear) harness connector.

SEF971Y

4. Disconnect ECM harness connector.
5. Check harness continuity between ECM terminal and HO2S2 terminal as follows.

Refer to Wiring Diagram.

MTBL0525

Continuity should exist.

6. Check harness continuity between ECM terminal or HO2S2 terminal and ground as follows.

Refer to Wiring Diagram.

MTBL0526

Continuity should not exist.

7. 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.

GI

MA

EM

LC

FE

AT

TF

PD

AX

SU

BR

ST

RS

BT

HA

SC

EL

IDX

DTC P0139, P0159 HEATED OXYGEN SENSOR 2 (REAR) (BANK 1)/(BANK 2)

(RESPONSE MONITORING)

Diagnostic Procedure (Cont’d)

EC-273

4

CHECK HO2S2 (REAR) GROUND CIRCUIT FOR OPEN AND SHORT

1. Check harness continuity between HO2S2 terminal 4 and engine ground.

Refer to Wiring Diagram.

Continuity should exist.

2. Also check harness for short to power.

OK or NG

OK (With CONSULT-II)

©

GO TO 5.

OK (Without CONSULT-
II)

©

GO TO 6.

NG

©

Repair open circuit or short to power in harness or connectors

5

CHECK REAR HEATED OXYGEN SENSOR

With CONSULT-II

1. Start engine and drive vehicle at a speed of more than 70 km/h (43 MPH) for 2 consecutive minutes.
2. Stop vehicle with engine running.
3. Select “FUEL INJECTION” in “ACTIVE TEST” mode, and select “HO2S2 (B1)/(B2)” as the monitor item with CONSULT-

II.

4. Check “HO2S2 (B1)/(B2)” at idle speed when adjusting “FUEL INJECTION” to

±

25%.

SEF972Y

“HO2S2 (B1)/(B2)” should be above 0.62V at least once when the “FUEL INJECTION” is +25%.
“HO2S2 (B1)/(B2)” should be below 0.57V at least once when the “FUEL INJECTION” is −25%.

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.

DTC P0139, P0159 HEATED OXYGEN SENSOR 2 (REAR) (BANK 1)/(BANK 2)

(RESPONSE MONITORING)

Diagnostic Procedure (Cont’d)

EC-274