2002 ISUZU AXIOM Service Repair Manual

seats gas mileage jack points inflation pressure navigation clutch

Page 1145 of 2100

ISUZU AXIOM 2002 Service Repair Manual 6E±178
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
DTC P0134 ±HO2S Circuit Insufficient Activity Bank 1 Sensor 1
StepNo Ye s Value(s) Action
71. Ignition ªOFFº.
2. With the PCM disconne

Page 1146 of 2100

ISUZU AXIOM 2002 Service Repair Manual 6E±179
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC)
P0135 HO2S Heater Circuit Bank 1 Sensor 1
060R200054
Circuit Description
Heated oxygen sensors are used to minimize t

6E±179
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC)
P0135 HO2S Heater Circuit Bank 1 Sensor 1
060R200054
Circuit Description
Heated oxygen sensors are used to minimize the amount
of time required for ªclosed loopº fuel control operation
and to allow accurate catalyst monitoring. The oxygen
sensor heater greatly decreases the amount of time
required for fuel control sensors Bank 1 HO2S 1 and Bank
2 HO2S 1 to become active. Oxygen sensor heaters are
required by post-catalyst monitor sensors to maintain a
sufficiently high temperature which allows accurate
exhaust oxygen content readings further from the engine.
The powertrain control module (PCM) will run the heater
test only after a cold start (determined by engine coolant
and intake air temperature at the time of start-up) and only
once during an ignition cycle. When the engine is started
the PCM will monitor the HO2S voltage. When the HO2S
voltage indicates a sufficiently active sensor, the PCM
looks at how much time has elapsed since start-up. If the
PCM determines that too much time was required for the
Bank 1 HO2S 1 to become active, a DTC P0135 will set.
The time it should take the HO2S to reach operating
temperature is based on the accumulated amount of air
that has passed through the MAF sensor and into the
engine (more accumulated air flow = shorter time to
HO2S activity).
Conditions for Setting the DTC
The engine has been running for over 120 seconds.
Heater signal is below 0.1A.
Bank 1 HO2S 1 voltage does not change more than
150 mV from the bias voltage (between 400 mV and
500 mV) for a longer amount of time than it should. The
maximum amount of time to come up to operating
range is 150 seconds. This warm-up time depends on
the engine coolant temperature at start-up and
accumulate air flow since start-up.
Action Taken When the DTC Sets
The PCM will illuminate the malfunction indicator lamp
(MIL) after the second consecutive trip in which the
fault is detected.
The PCM will store conditions which were present
when the DTC was set as Freeze Frame and in the
Failure Records data.
Conditions for Clearing the MIL/DTC
The PCM will turn the MIL ªOFFº on the third
consecutive trip cycle during which the diagnostic has
been run and the fault condition is no longer present.
A history DTC P0135 will clear after 40 consecutive
warm-up cycles have occurred without a fault.
DTC P0135 can be cleared by using the Tech 2 ªClear
Infoº function or by disconnecting the PCM battery
feed.

Page 1147 of 2100

ISUZU AXIOM 2002 Service Repair Manual 6E±180
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Aids
Check for the following conditions:
Poor connection at PCM ± Inspect harness connectors
for backed-out terminals, improper mating,

6E±180
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Aids
Check for the following conditions:
Poor connection at PCM ± Inspect harness connectors
for backed-out terminals, improper mating, broken
locks, improperly formed or damaged terminals, and
poor terminal-to-wire connection.
Damaged harness ± Inspect the wiring harness for
damage. If the harness appears to be OK, observe the
ECT display on the Tech 2 while moving connectors
and wiring harnesses related to the sensor. A change
in the display will indicate the location of the fault.
Reviewing the Failure Records vehicle mileage since the
diagnostic test last failed may help determine how often
the condition that caused the DTC to be set occurs. This
may assist in diagnosing the condition.
Test Description
Number(s) below refer to the step number(s) on the
Diagnostic Chart.2. The HO2S should be allowed to cool before
performing this test. If the HO2S heater is
functioning, the signal voltage will gradually increase
or decrease as the sensor element warms. If the
heater is not functioning, the HO2S signal will
remain near the 450 mV bias voltage.
4. Ensures that the ignition feed circuit to the HO2S is
not open or shorted. The test light should be
connected to a good chassis ground, in case the
HO2S low or HO2S heater ground circuit is faulty.
5. Checks the HO2S heater ground circuit.
6. Checks or an open or shorted HO2S heater element.
10.An open HO2S signal or low circuit can cause the
HO2S heater to appear faulty. Check these circuits
before replacing the sensor.
DTC P0135 ± HO2S Heater Circuit Bank 1 Sensor 1
StepActionValue(s)Ye sNo
1Was the ªOn-Board Diagnostic (OBD) System Checkº
performed?
ÐGo to Step 2
Go to OBD
System
Check
2NOTE: If the engine has just been operating ,allow the
engine to cool for at least 15 minutes before
proceeding.
1. Remove the fuel pump relay.
2. Connect a fused jumper at the fuel pump relay
socket, between the battery positive at the relay and
the relay wire that leads to the fuel pump and HO2S
fuses.
3. Ignition ªOFFº.
4. Install a Tech 2.
5. Ignition ªONº, engine ªOFFº.
6. Monitor the Bank 1 HO2S 1 voltage for several
minutes.
Did the HO2S voltage go from bias voltage to above or
below the specified values?
Above
650 mV or
below
250 mV
Refer to
Diagnostic
Aids
Go to Step 3
3Inspect the fuse for the Bank 1 HO2S 1 ignition feed.
Is the fuse open?
ÐGo to Step 15Go to Step 4
41. Ignition ªOFFº.
2. Raise the vehicle.
3. Disconnect the Bank 1 HO2S 1 electrical connector.
4. Using a test light connected to a good ground (do
not use Bank 1 HO2S 1 heater ground or Bank 1
HO2S 1 low), probe the ignition feed circuit at the
Bank 1 HO2S 1 electrical connector (PCM harness
side).
Does the test light illuminate?
ÐGo to Step 5Go to Step 7
5Connect the test light between the Bank 1 HO2S 1
ignition feed and the Bank 1 HO2S 1 heater ground.
Does the test light illuminate?
ÐGo to Step 6Go to Step 8

Page 1148 of 2100

ISUZU AXIOM 2002 Service Repair Manual 6E±181
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
DTC P0135 ± HO2S Heater Circuit Bank 1 Sensor 1
StepNo Ye s Value(s) Action
61. Allow the HO2S to cool for at least 15 minutes.
2. Using

Page 1149 of 2100

ISUZU AXIOM 2002 Service Repair Manual 6E±182
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC)
P0137 HO2S Circuit Low Voltage Bank 1 Sensor 2
060R200054
Circuit Description
The powertrain control module (PCM) sup

6E±182
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC)
P0137 HO2S Circuit Low Voltage Bank 1 Sensor 2
060R200054
Circuit Description
The powertrain control module (PCM) supplies bias
voltage of about 450 mV between the heated oxygen
sensor (HO2S) signal high and signal low circuits. When
measured with a 10 megaohm impedance digital
voltmeter, this may display as low as 350 mV. The
oxygen sensor varies the voltage within a range of about
1000 mV when exhaust is rich, down through about
10 mV when the exhaust is lean. The PCM constantly
monitors the HO2S signal during ªclosed loopº operation
and compensates for a rich or lean condition by
decreasing or increasing injector pulse width as
necessary. If the Bank 1 HO2S 2 signal voltage remains
excessively low for an extended period of time, DTC
P0137 will be set.
Conditions for Setting the DTC
No related DTCs.
Engine is operating in ªclosed loopº.
Engine coolant temperature is above 60C (140F).
ªClosed loopº commanded air/fuel ratio is between
14.5 and 14.8.
Throttle angle is between 3% and 19%.
Bank 1 HO2S 2 signal voltage remains below 22 mV
during normal ªclosed loopº operation for a total of 106
seconds over a 125-second period of time.
ORBank 1 HO2S 2 signal voltage remains below 400 mV
during power enrichment mode fuel control operation
for up to 5 seconds.
Action Taken When the DTC Sets
The PCM will ON the MIL after second trip with
detected fault.
The PCM will store conditions which were present
when the DTC set as Freeze Frame and in the Failure
Records data.
Conditions for Clearing the MIL/DTC
The PCM will turn the MIL ªOFFº on the third
consecutive trip cycle during which the diagnostic has
been run and the fault condition is no longer present.
A history DTC P0137 will clear after 40 consecutive
warm-up cycles have occurred without a fault.
DTC P0137 can be cleared by using the Tech 2 ªClear
Infoº function or by disconnecting the PCM battery
feed.
Diagnostic Aids
Check for the following conditions:
Heated oxygen sensor wiring ± The sensor pigtail may
be mispositioned and contacting the exhaust system.
Poor PCM to engine grounds.
Fuel pressure ± A condition which causes a lean
exhaust can cause DTC P0137 to set. The system will
go lean if pressure is too low. The PCM can

Page 1150 of 2100

ISUZU AXIOM 2002 Service Repair Manual 6E±183
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
compensate for some decrease. However, if fuel
pressure is too low, a DTC P0137 may be set. Refer
to
Fuel System Diagnosis.
Lean injector(s) ±

6E±183
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
compensate for some decrease. However, if fuel
pressure is too low, a DTC P0137 may be set. Refer
to
Fuel System Diagnosis.
Lean injector(s) ± Perform ªInjector Balance Testº.
Vacuum leaks ± Check for disconnected or damaged
vacuum hoses and for vacuum leaks at the intake
manifold, throttle body, EGR system, and PCV system.
Exhaust leaks ± An exhaust leak may cause outside air
to be pulled into the exhaust gas stream past the
HO2S, causing the DTC P0137 to set. Check for
exhaust leaks near the Bank 1 HO2S 2 sensor.
MAF sensor ± The system can go lean if the MAF
sensor signal indicates an engine airflow
measurement that is not correct. Disconnect the MAF
sensor to see if the lean condition is corrected. If so,
replace the MAF sensor.
Fuel contamination ± Water, even in small amounts,
can be delivered to the fuel injectors. The water can
cause a lean exhaust to be indicated. Excessivealcohol in the fuel can also cause this condition. Refer
to Fuel System Diagnosis for procedure to check for
fuel contamination.
If none of the above conditions are present, replace the
affected HO2S.
Test Description
Number(s) below refer to the step number(s) on the
Diagnostic Chart.
3. DTC P0137 failing during operation may indicate a
condition described in the ªDiagnostic Aidsº above.
If the DTC0137 test passes while the Failure
Records conditions are being duplicated, an
intermittent condition is indicated.
Reviewing the Failure Records vehicle mileage since the
diagnostic test last failed may help determine how often
the condition that caused the DTC to be set occurs. This
may assist in diagnosing the condition.
DTC P0137 ±HO2S Circuit Low Voltage Bank 1 Sensor 2
StepActionValue(s)Ye sNo
1Was the ªOn-Board Diagnostic (OBD) System Checkº
performed?
ÐGo to Step 2
Go to OBD
System
Check
21. Install the Tech 2.
2. Run the engine at operating temperature.
3. Operate the vehicle within the parameters specified
under ªConditions for Setting the DTCº criteria
included in Diagnostic Support.
4. Using a Tech 2, monitor Bank 1 HO2S 2 voltage.
Does the Bank 1 HO2S voltage remain below the
specified value?
22 mVGo to Step 4Go to Step 3
31. Ignition ªONº, engine ªOFFº, review and record
Tech 2 Failure Records data and note parameters.
2. Operate the vehicle within Failure Records
conditions as noted.
3. Using a Tech 2, monitor ªDTCº info for DTC P0137
until the DTC P0137 test runs.
4. Note the test result.
Does the Tech 2 indicate DTC P0137 failed this
ignition?
ÐGo to Step 4
Refer to
Diagnostic
Aids
41. Turn ignition ªOFFº.
2. Disconnect the PCM.
3. Check the Bank 1 HO2S 2 high and low signal
circuits for a short to ground or a short to the heater
ground circuit.
Were Bank 1 HO2S 2 signal circuits shorted?
ÐGo to Step 5Go to Step 6
5Repair the Bank 1 HO2S 2 signal circuit.
Is the action complete?
ÐVerify repairÐ
61. Ignition ªOFFº.
2. Leave the PCM and HO2S 2 disconnected.
3. Check for continuity between the high and low
signal circuits.
Was there continuity between the high and low circuits?
ÐGo to Step 7Go to Step 8

Page 1151 of 2100

ISUZU AXIOM 2002 Service Repair Manual 6E±184
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
DTC P0137 ±HO2S Circuit Low Voltage Bank 1 Sensor 2
StepNo Ye s Value(s) Action
7Repair the short between the high and low circuits.
Is t

Page 1152 of 2100

ISUZU AXIOM 2002 Service Repair Manual 6E±185
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC)
P0138 HO2S Circuit High Voltage Bank 1 Sensor 2
060R200054
Circuit Description
The powertrain control module (PCM) su

6E±185
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC)
P0138 HO2S Circuit High Voltage Bank 1 Sensor 2
060R200054
Circuit Description
The powertrain control module (PCM) supplies bias
voltage of about 450 mV between the heated oxygen
sensor (HO2S) signal high and signal low circuits. When
measured with a 10 megaohm digital voltmeter, this may
display as low as 320 mV. The oxygen sensor varies the
voltage within a range of about 1000 mV when exhaust is
rich, down through about 10 mV when the exhaust is
lean. The PCM constantly monitors the HO2S signal
during ªclosed loopº operation and compensates for a rich
or lean condition by decreasing or increasing injector
pulse width as necessary. If the Bank 1 HO2S 2 voltage
remains excessively high for an extended period of time,
DTC P0138 will be set.
Conditions for Setting the DTC
No related DTCs.
Engine is operating in ªclosed loopº.
ªClosed loopº commanded air/fuel ratio is between
14.5 and 14.8.
Engine coolant temperature is above 60C (140F).
Throttle angle is between 3% and 19%.
Bank 1 HO2S 2 signal voltage remains above 952 mV
during normal ªclosed loopº operation for a total of 106
seconds over a 125-second period of time.
ORBank 1 HO2S 2 signal voltage remains above 500 mV
during deceleration fuel cut±off mode operation for up
to 3 seconds.
Action Taken When the DTC Sets
The PCM will ON the MIL after second trip with
detected fault.
The PCM will store conditions which were present
when the DTC was set as Freeze Frame and in the
Failure Records data.
Conditions for Clearing the MIL/DTC
The PCM will turn the MIL ªOFFº on the third
consecutive trip cycle during which the diagnostic has
been run and the fault condition is no longer present.
A history DTC P0138 will clear after 40 consecutive
warm-up cycles have occurred without a fault.
DTC P0138 can be cleared by using the Tech 2 ªClear
Infoº function or by disconnecting the PCM battery
feed.
Diagnostic Aids
Check for the following conditions:
Fuel pressure ± An excessively rich fuel mixture can
cause a DTC P0138 to be set. Refer to
Fuel System
Diagnosis.
Rich injector(s) ± Perform ªInjector Balance Testº.
Leaking injector ± Refer to
Fuel System Diagnosis.

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