EC-44
POSITIVE CRANKCASE VENTILATION
Revision: 2006 November2007 350Z
POSITIVE CRANKCASE VENTILATIONPFP:11810
DescriptionNBS0002W
SYSTEM DESCRIPTION
This system returns blow-by gas to the intake manifold.
The positive crankcase ventilation (PCV) valve is provided to conduct crankcase blow-by gas to the intake
manifold. During partial throttle operation of the engine, the intake manifold sucks the blow-by gas through the
PCV valve. Normally, the capacity of the valve is sufficient to handle any blow-by and a small amount of venti-
lating air. The ventilating air is then drawn from the air inlet tubes into the crankcase. In this process the air
passes through the hose connecting air inlet tubes to rocker cover. Under full-throttle condition, the manifold
vacuum is insufficient to draw the blow-by flow through the valve. The flow goes through the hose connection
in the reverse direction.
On vehicles with an excessively high blow-by, the valve does not
meet the requirement. This is because some of the flow will go
through the hose connection to the air inlet tubes under all condi-
tions.
1. PCV valve 2. Electric throttle control actuator 3. Mass air flow sensor
A. Normal condition B. Hi-load condition
:Fresh air
:Blow-by air
PBIB3536E
PBIB1588E
DTC P0137, P0157 HO2S2
EC-287
C
D
E
F
G
H
I
J
K
L
MA
EC
Revision: 2006 November2007 350Z
DTC P0137, P0157 HO2S2PFP:226A0
Component DescriptionNBS000CW
The heated oxygen sensor 2, after three way catalyst 1, monitors the
oxygen level in the exhaust gas on each bank.
Even if switching characteristics of the air fuel ratio (A/F) sensor 1
are shifted, the air-fuel ratio is controlled to stoichiometric, by the sig-
nal from the heated oxygen sensor 2.
This sensor is made of ceramic zirconia. The zirconia generates volt-
age from approximately 1V in richer conditions to 0V in leaner condi-
tions.
Under normal conditions the heated oxygen sensor 2 is not used for
engine control operation.
CONSULT-III Reference Value in Data Monitor ModeNBS000CX
Specification data are reference values.
On Board Diagnosis LogicNBS000CY
The heated oxygen sensor 2 has a much longer switching time
between rich and lean than the air fuel ratio (A/F) sensor 1. The oxy-
gen storage capacity before the three way catalyst 1 causes the
longer switching time. To judge the malfunctions of heated oxygen
sensor 2, ECM monitors whether the maximum voltage of the sensor
is sufficiently high during the various driving condition such as fuel-
cut.
SEF327R
MONITOR ITEM CONDITION SPECIFICATION
HO2S2 (B1)
HO2S2 (B2)
Revving engine from idle to 3,000 rpm quickly after the following condi-
tions are met
–Engine: After warming up
–Keeping the engine speed between 3,500 and 4,000 rpm for 1 minute and
at idle for 1 minute under no load0 - 0.3V ←→ Approx. 0.6 -
1.0V
HO2S2 MNTR(B1)
HO2S2 MNTR(B2)
Revving engine from idle to 3,000 rpm quickly after the following condi-
tions are met
–Engine: After warming up
–Keeping the engine speed between 3,500 and 4,000 rpm for 1 minute and
at idle for 1 minute under no loadLEAN ←→ RICH
SEF259VA
DTC No. Trouble diagnosis name DTC detecting condition Possible cause
P0137
0137
(Bank 1)
Heated oxygen sensor
2 circuit low voltageThe maximum voltage from the sensor is not
reached to the specified voltage.
Harness or connectors
(The sensor circuit is open or shorted)
Heated oxygen sensor 2
Fuel pressure
Fuel injector
Intake air leaks P0157
0157
(Bank 2)
EC-298
DTC P0138, P0158 HO2S2
Revision: 2006 November2007 350Z
DTC P0138, P0158 HO2S2PFP:226A0
Component DescriptionNBS001NK
The heated oxygen sensor 2, after three way catalyst 1, monitors the
oxygen level in the exhaust gas on each bank.
Even if switching characteristics of the air fuel ratio (A/F) sensor 1
are shifted, the air-fuel ratio is controlled to stoichiometric, by the sig-
nal from the heated oxygen sensor 2.
This sensor is made of ceramic zirconia. The zirconia generates volt-
age from approximately 1V in richer conditions to 0V in leaner condi-
tions.
Under normal conditions the heated oxygen sensor 2 is not used for
engine control operation.
CONSULT-III Reference Value in Data Monitor ModeNBS001NL
Specification data are reference values.
On Board Diagnosis LogicNBS001NM
The heated oxygen sensor 2 has a much longer switching time between rich and lean than the air fuel ratio (A/
F) sensor 1. The oxygen storage capacity of the three way catalyst 1 causes the longer switching time.
MALFUNCTION A
To judge the malfunctions of heated oxygen sensor 2, ECM monitors
whether the voltage is unusually high during the various driving con-
dition such as fuel-cut.
MALFUNCTION B
To judge the malfunctions of heated oxygen sensor 2, ECM monitors
whether the minimum voltage of sensor is sufficiently low during the
various driving condition such as fuel-cut.
SEF327R
MONITOR ITEM CONDITION SPECIFICATION
HO2S2 (B1)
HO2S2 (B2)
Revving engine from idle to 3,000 rpm quickly after the following conditions
are met
–Engine: After warming up
–Keeping the engine speed between 3,500 and 4,000 rpm for 1 minute and at
idle for 1 minute under no load0 - 0.3V ←→ Approx. 0.6 -
1.0V
HO2S2 MNTR(B1)
HO2S2 MNTR(B2)
Revving engine from idle to 3,000 rpm quickly after the following conditions
are met
–Engine: After warming up
–Keeping the engine speed between 3,500 and 4,000 rpm for 1 minute and at
idle for 1 minute under no loadLEAN ←→ RICH
PBIB1848E
PBIB2376E
DTC P0139, P0159 HO2S2
EC-313
C
D
E
F
G
H
I
J
K
L
MA
EC
Revision: 2006 November2007 350Z
DTC P0139, P0159 HO2S2PFP:226A0
Component DescriptionNBS0006R
The heated oxygen sensor 2, after three way catalyst 1, monitors the
oxygen level in the exhaust gas on each bank.
Even if switching characteristics of the air fuel ratio (A/F) sensor 1
are shifted, the air-fuel ratio is controlled to stoichiometric, by the sig-
nal from the heated oxygen sensor 2.
This sensor is made of ceramic zirconia. The zirconia generates volt-
age from approximately 1V in richer conditions to 0V in leaner condi-
tions.
Under normal conditions the heated oxygen sensor 2 is not used for
engine control operation.
CONSULT-III Reference Value in Data Monitor ModeNBS0006S
Specification data are reference values.
On Board Diagnosis LogicNBS0006T
The heated oxygen sensor 2 has a much longer switching time
between rich and lean than the air fuel ratio (A/F) sensor 1. The oxy-
gen storage capacity before the three way catalyst 1 causes the
longer switching time. To judge the malfunctions of heated oxygen
sensor 2, ECM monitors whether the switching response of the sen-
sor's voltage is faster than specified during the various driving condi-
tion such as fuel-cut.
SEF327R
MONITOR ITEM CONDITION SPECIFICATION
HO2S2 (B1)
HO2S2 (B2)
Revving engine from idle to 3,000 rpm quickly after the following condi-
tions are met
–Engine: After warming up
–Keeping the engine speed between 3,500 and 4,000 rpm for 1 minute and
at idle for 1 minute under no load0 - 0.3V ←→ Approx. 0.6 -
1.0V
HO2S2 MNTR(B1)
HO2S2 MNTR(B2)
Revving engine from idle to 3,000 rpm quickly after the following condi-
tions are met
–Engine: After warming up
–Keeping the engine speed between 3,500 and 4,000 rpm for 1 minute and
at idle for 1 minute under no loadLEAN ←→ RICH
SEF302U
DTC No. Trouble diagnosis name DTC detecting condition Possible cause
P0139
0139
(Bank 1)
Heated oxygen sensor
2 circuit slow responseIt takes more time for the sensor to respond
between rich and lean than the specified time.
Harness or connectors
(The sensor circuit is open or shorted)
Heated oxygen sensor 2
Fuel pressure
Fuel injector
Intake air leaks P0159
0159
(Bank 2)
EC-406
DTC P0420, P0430 THREE WAY CATALYST FUNCTION
Revision: 2006 November2007 350Z
DTC P0420, P0430 THREE WAY CATALYST FUNCTIONPFP:20905
On Board Diagnosis LogicNBS0008K
The ECM monitors the switching frequency ratio of air fuel ratio (A/F) sensor 1 and heated oxygen sensor 2.
A three way catalyst 1 with high oxygen storage capacity will indicate a low switching frequency of heated oxy-
gen sensor 2. As oxygen storage capacity decreases, the heated oxygen sensor 2 switching frequency will
increase.
When the frequency ratio of air fuel ratio (A/F) sensor 1 and heated oxygen sensor 2 approaches a specified
limit value, the three way catalyst 1 malfunction is diagnosed.
DTC Confirmation ProcedureNBS0008L
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-III
TESTING CONDITION:
Do not hold engine speed for more than the specified minutes below.
1. Turn ignition switch ON and select “DATA MONITOR” mode with CONSULT-III.
2. Start engine and warm it up to the normal operating temperature.
3. Turn ignition switch OFF and wait at least 10 seconds.
4. Start engine and keep the engine speed between 3,500 and 4,000 rpm for at least 1 minute under no load.
5. Let engine idle for 1 minute.
6. Make sure that “COOLAN TEMP/S” indicates more than 70°C (158°F).
If not, warm up engine and go to next step when “COOLAN TEMP/S” indication reaches to 70°C (158°F).
7. Open engine hood.
8. Select “DTC & SRT CONFIRMATION” then “SRT WORK SUPPORT” mode with CONSULT-III.
9. Rev engine up to 2,000 to 3,000 rpm and hold it for 3 consecutive minutes then release the accelerator
pedal completely.
If “INCMP” of “CATALYST” changed to “CMPLT”, go to step 12.
10. Wait 5 seconds at idle.
11. Rev engine up to 2,000 to 3,000 rpm and maintain it until “INCMP” of “CATALYST” changes to “CMPLT” (It
will take approximately 5 minutes).
If not “CMPLT”, stop engine and cool it down to less than 70°C (158°F) and then retest from step 1.
12. Select “SELF-DIAG RESULTS” mode with CONSULT-III.
DTC No. Trouble diagnosis name DTC detecting condition Possible cause
P0420
0420
(Bank 1)
Catalyst system effi-
ciency below threshold
Three way catalyst 1 does not operate prop-
erly.
Three way catalyst 1 does not have enough
oxygen storage capacity.
Three way catalyst 1
Exhaust tube
Intake air leaks
Fuel injector
Fuel injector leaks
Spark plug
Improper ignition timing P0430
0430
(Bank 2)
PBIB1923E