sensor ISUZU AXIOM 2002 Service Repair Manual

6E±162
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Aids
DTC P0125 set indicates a faulty ECT sensor.
Comparing the engine coolant temperature displayed on
a Tech 2 with actual coolant temperature measured with a
thermometer may isolate this condition. If the displayed
engine coolant temperature is not close to the actual
coolant temperature, replace the ECT sensor.
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
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.
If DTC P0125 cannot be duplicated, the information
included in the Failure Records data can be useful in
determining vehicle mileage wince the DTC was last set.
Test Description
Number(s) below refer to the step number(s) on the
Diagnostic Chart.
2. Comparing the engine coolant temperature displayed
on a Tech 2 with actual coolant temperature
measured with a thermometer may isolate this
condition. If the displayed engine coolant
temperature is not close to the actual coolant
temperature, replace the ECT sensor. If the
temperatures are close, the fault is intermittent;
refer to
Diagnostic Aids.
Engine Coolant Temperature

C
FOHMS
Temperature vs. Resistance Values
(approximate)
100212177
80176332
60140667
4511 31188
35951802
25772796
15594450
5417280
±52312300
±15521450
±30±2252700
±40±40100700
DTC P0125 ±ECT Excessive Time to Closed Loop Fuel Control

StepActionValue(s)Ye sNo
1Was the ªOn-Board Diagnostic (OBD) System Checkº
performed?
ÐGo to Step 2
Go to OBD
System
Check
2Are any ECT sensor DTCs set?
Ð
Go to
applicable
ECT sensor
DTC chart
Go to Step 3
31. Allow the engine to cool completely.
2. Check the cooling system coolant level (refer to
Cooling and Radiator).
Is the coolant level OK?
ÐGo to Step 4Go to Step 9
41. Start the engine.
2. With the engine idling, monitor ªENG COOL TEMPº
display on the Tech 2.
Does ªENG COOL TEMPº increase to above the
specified value within 2 minutes?
21
C (70
F)
Refer to
Diagnostic
Aids
Go to Step 5
5Check for proper operation of the thermostat (refer to
Cooling and Radiator).
Is the thermostat operating correctly?
ÐGo to Step 6Go to Step 9

6E±163
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
DTC P0125 ±ECT Excessive Time to Closed Loop Fuel Control

 
StepNo Ye s Value(s) Action
6Compare engine coolant temperature displayed on the
Tech 2 to the actual coolant temperature measured
with a thermometer. (Observe normal precautions
when opening the cooling system.)
Is the Tech 2 engine coolant temperature indication
close to the measured temperature?
ÐGo to Step 9Go to Step 7
71. Ignition ªOFFº.
2. Disconnect the PCM.
3. Using a DVM, measure the resistance of the ECT at
the PCM connector.
4. Compare the DVM reading with the chart in ªTest
Descriptionº.
Is the chart value approximately equal to the
thermometer reading?
ÐGo to Step 12Go to Step 8
8Check for high resistance in wiring related to the ECT
sensor. Also, check for poor connections at the ECT
sensor and the PCM.
Was a problem found?
ÐGo to Step 10Go to Step 11
9Refer to Cooling and Radiator for cooling system
diagnosis and repair condition as necessary.
Is the action complete?
ÐVerify repairÐ
10Replace the faulty terminal(s) or repair faulty wiring as
necessary.
Is the action complete?
ÐVerify repairÐ
11Replace the ECT sensor.
Is the action complete?
ÐVerify repairÐ
12Replace the PCM.
IMPORTANT:The replacement PCM must be
programmed. Refer to
On-Vehicle Service in
Powertrain Control Module and Sensors for
procedures.
And also refer to latest Service Bulletin.
Check to see if the Latest software is released or not.
And then Down Load the LATEST PROGRAMMED
SOFTWARE to the replacement PCM.
Is the action complete?
ÐVerify repairÐ

6E±164
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code(DTC)
P0128 Thermostat Insufficient Temperature for Stable Operation
060R200053
Circuit Description

The engine coolant temperature (ECT) sensor
thermistor mounted on a coolant crossover pipe at the
front of the engine.
This code determines if system has insufficient
coolant temperatures for stable operation.
Conditions for setting the DTC

Engine running.

No IAT, ECT and MAF DTCs set.

No VSS DTC set.
Warm case(Ambient temperature is between 50
F and
128
F.):

Time for coolant to reach stabilized closed loop value
is less than 239 sec.
Cold case(Ambient temperature is between 20
F and
50
F.):

Time for coolant to reach stabilized thermostat
regulation temperature is more than 263 sec.
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 P0128 will clear after 40 consecutive trip
cycles during which the warm up cycles have occurred
without a fault.

DTC P0128 can be cleared using the Tech 2 ªClear
Infoº function or by disconnecting the PCM battery
feed.
Tech 2 ªClear Infoº function or by disconnecting the
PCM battery feed.
Diagnostic Aids
An intermittent may be caused by the following:

Poor connections.

Misrouted harness.

Rubbed through wire insulation.

Broken wire inside the insulation.
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.

6E±165
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
If the harness appears to be OK, observe the ECT
display on the Tech2 while moving connectors and
wiring harnesses related to the sensor.
A change in the display will indicate the location of
the fault.
If DTC P0128 cannot be duplicated, the information
included in the Failure Records data can be useful indetermined vehicle mileage since the DTC was last
set.
If it is determined that the DTC occurs intermittently,
performing the DTC P0128 Diagnostic Chart may
isolate the cause of the fault.
Diagnostic Trouble Code (DTC)
P0128 Thermostat Insufficient Temperature for stable operation

StepActionValue(s)Ye sNo
1Was the ªOn-Board(OBD)System Checkº performed?
ÐGo to Step 2
Go to OBD
System
Check
21. Visually/physically check air duct and water pipe for
splits, kinks, and proper connections and routing.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 3
31. Remove and check the Thermostat for stable
operation. Refer to
6B section.
2. Replace the thermostat if necessary.
Was a problem found?
ÐVerify repairGo to Step 4
41. Ignition ªONº, engine ªOFFº.
2. Review and record Tech 2 Failure Records.
3. Operate the vehicle within Failure Records
conditions as noted.
4. Using a Tech 2, monitor ªDTCº info for DTC P0128.
Does the Tech 2 indicate DTC P0128 failed this
ignition?
ÐGo to Step 5
Refer to
Diagnostic
Aids
51. Ignition ªONº, engine ªOFFº.
2. Oberve the ªEng Cool Tempº display on the Tech 2.
Is the ªEng Cool Tempº below the specified value?
139
C
(282
F)
Verify repairGo to Step 6
61. Ignition ªOFFº.
2. Disconnect the PCM and check the ECT signal
circuit for a short to ground or a short to the sensor
ground circuit.
3. If the ECT signal circuit is shorted, repair it as
necessary.
Was a problem found?
ÐVerify repair
Refer to Diag-
nostic
Go to Step 7
7Replace the PCM.
IMPORTANT:
The replacement PCM must be programmed.
Refer to
ON-Vehicle Service in Power Control Module
and Sensors for procedures.
And also refer to latest Service Bulletin.
Check to see if the latest software is released or not.
And then Down Load the LATEST PROGRAMMED
SOFTWARE to the replacement PCM.
Is the action complete?
ÐVerify repairÐ

6E±166
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC)
P0131 HO2S Circuit Low Voltage Bank 1 Sensor 1
060R200054
Circuit Description
The powertrain control module (PCM) supplies a 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 350 mV. The oxygen sensor varies the
voltage within a range of about 1000 mV when the
exhaust is rich, down through about 10 mV when 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 1 voltage
remains excessively low for an extended period of time,
DTC P0131 will be set.
Conditions for Setting the DTC

No related DTCs.

Vehicle is operating in ªclosed loopº.

Engine coolant temperature is above 60
C (140
F).

ªClosed loopº commanded air/fuel ratio is between
14.5 and 14.8.

Bank 1 HO2S 1 signal voltage remains below 22 mV
during normal ªclosed loopº operation for a total of 77
seconds over a 90-second period of time.
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.

ªOpen loopº fuel control will be in effect.
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 P0131 will clear after 40 consecutive
warm-up cycles have occurred without a fault.

DTC P0131 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 routed incorrectly and contacting the exhaust
system.

Poor PCM to engine block grounds.

Fuel pressure ± The system will go lean if pressure is
too low. The PCM can compensate for some
decrease. However, If fuel pressure is too low, a DTC
P0131 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.

6E±167
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS

Exhaust leaks ± An exhaust leak may cause outside air
to be pulled into the exhaust gas stream past the
HO2S, causing the system to appear lean. Check for
exhaust leaks that may cause a false lean condition to
be indicated.

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. Excessive
alcohol in the fuel can also cause this condition. Refer
to
Fuel System Diagnosis for the 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 step numbers on the diagnostic
chart.
3. DTC P0131 failing during operation may indicate a
condition described in the ªDiagnostic Aidsº above.
If the DTC P0131 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 P0131 ±HO2S Circuit Low Voltage 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
21. Install the Tech 2.
2. Run the engine at normal 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 1 voltage.
Does the Bank 1 HO2S 1 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 P0131
until the DTC P0131 test runs.
Note test result.
Does Tech 2 indicate DTC P0131 failed this ignition?
ÐGo to Step 4
Refer to
Diagnostic
Aids
41. Turn the ignition ªOFFº.
2. Disconnect the PCM.
3. Check the Bank 1 HO2S 1 high and low circuits for a
short to ground or a short to the heater ground
circuit.
Are the Bank 1 HO2S 1 signal circuits shorted to
ground?
ÐGo to Step 5Go to Step 6
5Repair the Bank 1 HO2S 1 signal circuit.
Is the action complete?
ÐVerify repairÐ
61. Turn the ignition ªOFFº, HO2S 1 and PCM
disconnected.
2. Check for short circuit between the high and low
signal circuits.
Was there continuity between the high and low circuits?
ÐGo to Step 7Go to Step 8
7Repair the short between the high and low circuits.
Is the action complete?
ÐVerify repairÐ

6E±168
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
DTC P0131 ±HO2S Circuit Low Voltage Bank 1 Sensor 1

 
StepNo Ye s Value(s) Action
81. Ignition ªOFFº.
2. Reconnect the PCM, leave the sensor
disconnected.
3. Ignition ªONº.
Does the Tech 2 indicate Bank 1 HO2S 1 voltage
between the specified values?
425-475 mV
Refer to
Diagnostic
Aids
Go to Step 9
9Replace the PCM.
IMPORTANT:The replacement PCM must be
programmed. Refer to
On-Vehicle Service in
Powertrain Control Module and Sensors for
procedures.
And also refer to latest Service Bulletin.
Check to see if the Latest software is released or not.
And then Down Load the LATEST PROGRAMMED
SOFTWARE to the replacement PCM.
Is the action complete?
ÐVerify repairÐ

6E±169
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC)
P0132 HO2S Circuit High Voltage Bank 1 Sensor 1
060R200054
Circuit Description
The powertrain control module (PCM) supplies a bias
voltage of about 450 mV between the heated oxygen
sensor (HO2S) signal and 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 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 1 voltage remains
excessively high for an extended period of time, DTC
P0132 will be set.
Conditions for Setting the DTC

No related DTCs.

Engine coolant temperature is above 60
C (140
F)

ªClosed loopº commanded air/fuel ratio is between
14.5 and 14.8.

Bank 1 HO2S 1 signal voltage remains above 952 mV
during normal ªclosed loopº operation for a total of 77
seconds over a 90-second period.
OR

Bank 1 HO2S 1 signal voltage remains above 500 mV
during ªdeceleration fuel cutoff modeº operation for 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.

ªOpen loopº fuel control will be in effect.
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 P0132 will clear after 40 consecutive
warm-up cycles have occurred without a fault.

DTC P0132 can be cleared by using the Tech 2 ªClear
Infoº function or by disconnecting the PCM battery
feed.
Diagnostic Aids
Check the following items:

Fuel pressure ± The system will go rich if pressure is
too high. The PCM can compensate for some
increase. However, if fuel pressure is too high, a DTC
P0132 may be set. Refer to
Fuel System Diagnosis.

Perform ªInjector Balance Testº ± Refer to
Fuel System
Diagnosis.

6E±170
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS

Check the EVAP canister for fuel saturation ± If full of
fuel, check canister control and hoses. Refer to
Evaporative (EVAP) Emission Control System.

MAF sensor ±The system can go rich if MAF sensor
signal indicates an engine airflow measurement that is
not correct. Disconnect the MAF sensor to see it the
rich condition is corrected. If so, replace the MAF
sensor.

Check for a leak in the fuel pressure regulator
diaphragm by checking the vacuum line to the
regulator for the presence of fuel. There should be no
fuel in the vacuum line.

An intermittent TP sensor output will cause the system
to go rich due to a false indication of the engine
acceleration.

Shorted Heated Oxygen Sensor (HO2S) ±If the HO2S
is internally shorted, the HO2S voltage displayed on
the Tech 2 will be over 1 volt. Try disconnecting the
affected HO2S with the key ªONº, engine ªOFFº. If the
displayed HO2S voltage changes from over 1000 mV
to around 450 mV, replace the HO2S. Silicon
contamination of the HO2S can also cause a high
HO2S voltage to be indicated. This condition is
indicated by a powdery deposit on the portion of the
HO2S exposed to the exhaust stream. If
contamination is noticed, replace the affected HO2S.

Open HO2S Signal Circuit or Faulty HO2S±A poor
connection or open in the HO2S signal circuit cancause the DTC to set during deceleration fuel mode.
An HO2S which is faulty and not allowing a full voltage
swing between the rich and lean thresholds can also
cause this condition. Operate the vehicle by
monitoring the HO2S voltage with a Tech 2. If the
HO2S voltage is limited within a range between 300
mV to 600 mV, check the HO2S signal circuit wiring
and associated terminal conditions.

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 P0132 failing during ªdeceleration fuel cutoff
modeº operation may indicate a condition described
in the ªDiagnostic Aidsº above. If the DTC P0132
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 P0132 ± HO2S Circuit High Voltage 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
21. Install the Tech 2.
2. Run the engine at operating temperature.
3. Operate the vehicle within parameters specified
under ªConditions for Setting the DTCº included in
Diagnostic Support.
4. Using a Tech 2, monitor Bank 1 HO2S 1 voltage.
Does the Bank 1 HO2S 1 voltage remain above the
specified value?
952 mV (500
mV in
deceleration
fuel cutoff
mode)
Go to Step 4Go to Step 3
31. Ignition ªONº, review and record Tech 2 Failure
Records data.
2. Operate the vehicle within Failure Records
conditions as noted.
3. Using a Tech 2, monitor ªDTCº info for DTC P0132
until the DTC P0132 test runs.
4. Note the test result.
Does the Tech 2 indicate DTC P0132 failed this
ignition?
ÐGo to Step 4
Refer to
Diagnostic
Aids
41. Ignition ªOFFº.
2. Disconnect Bank 1 HO2S 1.
3. Ignition ªONº.
4. At HO2S Bank 1 Sensor 1 connector (PCM side)
use a DVM to measure voltages at the high and low
signal terminals.
Are the voltages in the specified range?
3-4 VGo to Step 5Go to Step 6

6E±171
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
DTC P0132 ± HO2S Circuit High Voltage Bank 1 Sensor 1

 
StepNo Ye s Value(s) Action
5Repair short to voltage in signal circuit.
Is the action complete?
ÐVerify repairÐ
61. Ignition ªONº, engineªOFFº.
2. At Bank 1 HO2S 1 connector (PCM side) jumper
both the HO2S high and low signal circuits (PCM
side) to ground.
3. Using a Tech 2, monitor Bank 1 HO2S 1 voltage.
Is Bank 1 HO2S 1 voltage below the specified value?
10 mVGo to Step 7Go to Step 8
71. Disconnect the jumpers to ground from Bank 1
HO2S 1 PCM-side connector.
2. With the HO2S 1 connector disconnected, monitor
Bank 1 HO2S 1 voltage.
Is Bank 1 HO2S 1 voltage between the specified
values?
425-475 mV
Refer to
Diagnostic
Aids
Go to Step 8
8Replace the PCM.
IMPORTANT:The replacement PCM must be
programmed. Refer to
On-Vehicle Service in
Powertrain Control Module and Sensors for
procedures.
And also refer to latest Service Bulletin.
Check to see if the Latest software is released or not.
And then Down Load the LATEST PROGRAMMED
SOFTWARE to the replacement PCM.
Is the action complete?
ÐVerify repairÐ