Infiniti QX4 (R50). Manual — part 195
SEF327R
Component Description
NBEC0130
The heated oxygen sensor 2 (rear), after three way catalyst, moni-
tors the oxygen level in the exhaust gas on each bank.
Even if switching characteristics of the heated oxygen sensor 1
(front) are shifted, the air fuel ratio is controlled to stoichiometric,
by the signal from the heated oxygen sensor 2 (rear).
This sensor is made of ceramic zirconia. The zirconia generates
voltage from approximately 1V in richer conditions to 0V in leaner
conditions.
Under normal conditions the heated oxygen sensor 2 (rear) is not
used for engine control operation.
CONSULT-II Reference Value in Data Monitor
Mode
NBEC0131
Specification data are reference values.
MONITOR ITEM
CONDITION
SPECIFICATION
HO2S2 (B1)
HO2S2 (B2)
I
Engine: After warming up
Revving engine from idle up to
2,000 rpm
0 - 0.3V
+,
Approx. 0.6 - 1.0V
HO2S2 MNTR
(B1)
HO2S2 MNTR
(B2)
LEAN
+,
RICH
ECM Terminals and Reference Value
NBEC0658
Specification data are reference values and are measured between each terminal and ground.
CAUTION:
Do not use ECM ground terminals when measuring input/output voltage. Doing so may result in dam-
age to the ECM’s transistor. Use a ground other than ECM terminals, such as the ground.
TERMI-
NAL
NO.
WIRE
COLOR
ITEM
CONDITION
DATA (DC Voltage)
72
OR
Heated oxygen sensor
2 (rear) (bank 1)
[Engine is running]
I
Warm-up condition
I
Engine speed is 2,000 rpm.
0 - Approximately 1.0V
71
OR/L
Heated oxygen sensor
2 (rear) (bank 2)
[Engine is running]
I
Warm-up condition
I
Engine speed is 2,000 rpm.
0 - Approximately 1.0V
SEF304UB
On Board Diagnosis Logic
NBEC0133
The heated oxygen sensor 2 (rear) has a much longer switching
time between rich and lean than the heated oxygen sensor 1
(front). The oxygen storage capacity before the three way catalyst
causes the longer switching time. To judge the malfunctions of
heated oxygen sensor 2 (rear), ECM monitors whether the mini-
mum voltage of sensor is sufficiently low during the various driving
condition such as fuel-cut.
Malfunction is detected when the minimum voltage from the sen-
sor is not reached to the specified voltage.
GI
MA
EM
LC
FE
AT
TF
PD
AX
SU
BR
ST
RS
BT
HA
SC
EL
IDX
DTC P0137, P0157 HEATED OXYGEN SENSOR 2 (REAR) (BANK 1)/(BANK 2)
(MIN. VOLTAGE MONITORING)
Component Description
EC-247
Possible Cause
NBEC0438
I
Harness or connectors
(The sensor circuit is open or shorted.)
I
Heated oxygen sensor 2 (rear)
I
Fuel pressure
I
Injectors
SEF340Z
SEF341Z
SEF342Z
DTC Confirmation Procedure
NBEC0134
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.
TESTING CONDITION:
Open engine hood before conducting following procedure.
WITH CONSULT-II
NBEC0134S01
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”.
4)
Select “DATA MONITOR” mode with CONSULT-II.
5)
Make sure that “COOLAN TEMP/S” indicates more than 70°C
(158°F).
6)
Select “HO2S2 (B1)/(B2) P0137/P0157” of “HO2S2” in “DTC
WORK SUPPORT” mode with CONSULT-II.
7)
Start engine and follow the instruction of CONSULT-II.
8)
Make sure that “OK” is displayed after touching “SELF-DIAG
RESULTS”.
If NG is displayed, refer to “Diagnostic Procedure”, EC-252.
If “CANNOT BE DIAGNOSED” is displayed, perform the fol-
lowing.
a)
Stop engine and cool down until “COOLAN TEMP/S” indicates
less than 70°C (158°F).
b)
Turn ignition switch “ON”.
c)
Select “DATA MONITOR” mode with CONSULT-II.
d)
Start engine.
e)
Return to step 6 again when the “COOLAN TEMP/S” reaches
to 70°C (158°F).
SEF312XB
Overall Function Check
NBEC0135
Use this procedure to check the overall function of the heated oxy-
gen sensor 2 (rear) circuit. During this check, a 1st trip DTC might
not be confirmed.
WITH GST
NBEC0135S01
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)
Set voltmeter probes between ECM terminal 72 (HO2S2 bank
DTC P0137, P0157 HEATED OXYGEN SENSOR 2 (REAR) (BANK 1)/(BANK 2)
(MIN. VOLTAGE MONITORING)
Possible Cause
EC-248
1 right signal) or 71 (HO2S2 bank 2 left signal) and engine
ground.
4)
Check the voltage when racing up to 4,000 rpm under no load
at least 10 times.
(Depress and release accelerator pedal as soon as possible.)
The voltage should be below 0.57V at least once during
this procedure.
If the voltage can be confirmed in step 4, step 5 is not
necessary.
5)
Keep vehicle at idling for 10 minutes, then check the voltage.
Or check the voltage when coasting from 80 km/h (50 MPH)
in “D” position with “OD” OFF.
The voltage should be below 0.57V at least once during
this procedure.
6)
If NG, go to “Diagnostic Procedure”, EC-252.
GI
MA
EM
LC
FE
AT
TF
PD
AX
SU
BR
ST
RS
BT
HA
SC
EL
IDX
DTC P0137, P0157 HEATED OXYGEN SENSOR 2 (REAR) (BANK 1)/(BANK 2)
(MIN. VOLTAGE MONITORING)
Overall Function Check (Cont’d)
EC-249
Wiring Diagram
=NBEC0136
RIGHT BANK
NBEC0136S01
MEC951C
DTC P0137, P0157 HEATED OXYGEN SENSOR 2 (REAR) (BANK 1)/(BANK 2)
(MIN. VOLTAGE MONITORING)
Wiring Diagram
EC-250
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