ISUZU AXIOM 2002 Service Repair Manual

6E±214
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Aids
Check for the following conditions:

Fuel pressure ± An excessively rich fuel mixture can
cause a DTC P0158 to be set. Refer to
Fuel System
Diagnosis.

Rich injector(s) ± Perform ªInjector Balance Testº.

Leaking injector ± Refer to
Fuel System Diagnosis.

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

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

Check for a leaking 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.

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

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 isindicated 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 or low circuit, or faulty HO2S ± A
poor connection or open in the HO2S signal or low
circuit can cause the DTC to set during deceleration
fuel cutoff mode operation. An HO2S which is faulty
and does not allow full voltage swing between the rich
and lean thresholds can also cause this condition.
Operate the vehicle while 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 and low circuit wiring and associated terminal
connections. If the wiring and connections are OK,
replace the HO2S.

If none of 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 P0158 being set during deceleration fuel cutoff
mode operation may indicate a condition described
in the ªDiagnostic Aidsº above. If the DTC P0158
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 P0158 ± HO2S Circuit High Voltage Bank 2 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 parameters specified
under ªConditions for Setting the DTCº criteria
included in Diagnostic Support.
4. Using a Tech 2, monitor Bank 2 HO2S 2 voltage.
Does the Bank 2 HO2S 2 voltage remain above the
specified value?
952 mV
(500 mV in
deceleration
fuel cut-out
mode)
Go to Step 4Go to Step 3
31. Ignition ªONº.
2. Review and record Tech 2 Failure Records data.
3. Operate the vehicle within Failure Records
conditions as noted.
4. Using a Tech 2, monitor ªDTCº info for DTC P0158
until the DTC P0158 test runs.
5. Note the test result.
Does the Tech 2 indicate DTC P0158 failed this
ignition?
ÐGo to Step 4
Refer to
Diagnostic
Aids

6E±215
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
DTC P0158 ± HO2S Circuit High Voltage Bank 2 Sensor 2

 
StepNo Ye s Value(s) Action
41. Ignition ªOFFº.
2. Disconnect Bank 2 HO2S 2.
3. Ignition ªONº.
4. At the HO2S Bank 2 Sensor 2 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
5Repair short to voltage in signal circuit.
Is the action complete?
ÐVerify repairÐ
61. Ignition ªONº, engine ªOFFº.
2. At Bank 2 HO2S 2 connector (PCM side) jumper
both the HO2S high and low signal circuits (PCM
side) to ground.
3. Using a Tech 2, monitor Bank 2 HO2S 2 voltage.
Is Bank 2 HO2S 2 voltage below the specified value?
10 mVGo to Step 7Go to Step 8
71. Disconnect the jumpers to ground from Bank 2
HO2S 2 PCM-side connector.
2. With the HO2S 2 connector disconnected, monitor
Bank 2 HO2S 2 voltage.
Is Bank 2 HO2S 2 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 the 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±216
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC)
P0160 HO2S Circuit Insufficient Activity Bank 2 Sensor 2
060R200054
Circuit Description
To control emissions of hydrocarbons (HC), carbon
monoxide (CO), and oxides of nitrogen (NOx), a
three-way catalytic converter is used. The catalyst within
the converter promotes a chemical reaction which
oxidizes the HC and CO present in the exhaust gas,
converting them into harmless water vapor and carbon
dioxide. The catalyst also reduces NOx, converting it to
nitrogen. The powertrain control module (PCM) has the
ability to monitor this process using the Bank 2 HO2S 1
and the Bank 2 HO2S 2 heated oxygen sensors. The
Bank 2 HO2S 1 sensor produces an output signal which
indicates the amount of oxygen present in the exhaust
gas entering the three-way catalytic converter. The Bank
2 HO2S 2 sensor produces an output signal which
indicates the oxygen storage capacity of the catalyst; this
in turn indicates the catalyst's ability to convert exhaust
gases efficiently. If the catalyst is operating efficiently, the
Bank 2 HO2S 1 signal will be far more active than that
produced by the Bank 2 HO2S 2 sensor. If the Bank 2
HO2S 2 signal voltage remains between 400 mV and
500 mV for an extended period of time, DTC P0160 will be
set.
Heated Oxygen sensors are used to minimize the amount
of time required for ªclosed loopº fuel control operation
and allow accurate catalyst monitoring. The oxygen
sensor heater greatly decreases the amount of time
required for fuel control sensors Bank 1 HO2S 1 and Bank2 HO2S 1 to become active. Oxygen sensor heaters are
required by post-catalyst monitor sensors to maintain a
sufficiently high temperature for accurate exhaust oxygen
content readings further from the engine.
Conditions for Setting the DTC

No related DTCs.

Battery voltage is above 10 volts.

The engine has been running for over 5 seconds.

Oxygen sensor heater is functioning properly.

Engine is in ªclosed loopº operation.

Bank 2 HO2S 2 signal voltage remains between
426 mV and 474 mV for a total of 106 seconds over a
125-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.
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 P0160 will clear after 40 consecutive
warm-up cycles have occurred without a fault.

6E±217
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS

DTC P0160 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:

Poor connection or damaged harness ± Inspect the
harness connectors for backed-out terminals,
improper mating, broken locks, improperly formed or
damaged terminals, poor terminal-to-wire connection,
and damaged harness.

Faulty HO2S heater or heater circuit ± With the ignition
ªONº, engine ªOFFº, the HO2S voltage displayed on a
Tech 2 should gradually drop to below 250 mV. If not,
disconnect the HO2S and connect a test light between
the HO2S ignition feed and heater ground circuits. If
the test light does not light, repair the open ignition feed
or sensor ground circuit as necessary. If the test light
lights and the HO2S signal and low circuits are OK,
replace the HO2S.
Intermittent test ± With the ignition ªONº, monitor the
HO2S signal voltage while moving the wiring harness
and related connectors. If the fault is induced, the
HO2S signal voltage will change. This may help isolate
the location of the malfunction.Test Description
Number(s) below refer to the step number(s) on the
Diagnostic Chart.
3. If the DTC P0160 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 P0160 ± HO2S Circuit Insufficient Activity Bank 2 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 engine above 1200 RPM for two
minutes.
Does the Tech 2 indicate Bank 2 HO2S 2 voltage
varying outside the specified values?
425-475 mVGo to Step 3Go to Step 4
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 P0160
until the DTC P0160 test runs.
4. Note the test result.
Does the Tech 2 indicate DTC P0160 failed this
ignition?
ÐGo to Step 4
Refer to
Diagnostic
Aids
4Check for a damaged harness.
Was problem found?
ÐVerify repairGo to Step 5
5Check for poor Bank 2 HO2S 2 high and low circuit
terminal connections at the Bank 2 HO2S 2 harness
connector and replace terminal(s) if necessary.
Did either terminal require replacement?
ÐVerify repairGo to Step 6
6Check for poor Bank 2 HO2S 2 high and low circuit
terminal connections at the PCM and replace terminals
if necessary.
Did any terminals require replacement?
ÐVerify repairGo to Step 7

6E±218
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
DTC P0160 ± HO2S Circuit Insufficient Activity Bank 2 Sensor 2

 
StepNo Ye s Value(s) Action
71. Ignition ªOFFº.
2. With the PCM disconnected, check continuity of the
Bank 2 HO2S 2 high circuit.
3. If the Bank 2 HO2S 2 high circuit measures over 5.0
ohms, repair open or poor connections as
necessary.
Was a Bank 2 HO2S 2 high circuit problem found and
corrected?
ÐVerify repairGo to Step 8
81. Ignition ªOFFº.
2. With the PCM disconnected, check continuity of the
Bank 2 HO2S 2 low circuit.
3. If the Bank 2 HO2S 2 low circuit measures over 5
ohms, repair open or poor connections as
necessary.
Was a Bank 2 HO2S 2 low circuit problem found and
corrected?
ÐVerify repairGo to Step 9
91. Ignition ªONº, engine ªOFFº.
2. Disconnect Bank 2 HO2S 2 and jumper the HO2S
high and low circuits (PCM side) to ground.
3. Using a Tech 2, monitor Bank 2 HO2S 2 voltage.
Is Bank 2 HO2S 2 voltage in the specified range?
0-10 mVGo to Step 10Go to Step 11
10Replace Bank 2 HO2S 2.
Is the action complete?
ÐVerify repairÐ
11Replace 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 the 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±219
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC)
P0161 HO2S Heater Circuit Bank 2 Sensor 2
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 Bank 2
HO2S 2 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 2 HO2S 2 to become active, a DTC P0161
will set. The time it should take the HO2S to reach
operating temperature is based on the total amount of air
that has passed through the MAF sensor and into the
engine (more total air flow = shorter time to HO2S
activity).
Conditions for Setting the DTC

No related DTCs.

The engine has been running for over 120 seconds.
Ignition voltage is between 11 volts and 18 volts.

Average mass air flow for the sample period is less
than 23 g/second.

Bank 2 HO2S 2 voltage does not change more than
150 mV from the bias voltage (between
400 mV-500 mV) for a longer amount of time than it
should. The maximum amount of time to come up to
operating range is 120 seconds. This warm-up time
depends on the engine coolant temperature at start-up
and accumulated 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 P0161 will clear after 40 consecutive
warm-up cycles have occurred without a fault.

DTC P0161 can be cleared by using the Tech 2 ªClear
Infoº function or by disconnecting the PCM battery
feed.

6E±220
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
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. This 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. This checks the HO2S heater ground circuit.
6. This checks for an open or shorted HO2S heater
element.
11.An open HO2S signal or low circuit can cause the
HO2S heater to appear faulty. Check these circuits
before replacing the sensor.
DTC P0161 ± HO2S Heater Circuit Bank 2 Sensor 2

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 2 HO2S 2 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 2 HO2S 2 ignition feed.
Is the fuse open?
ÐGo to Step 15Go to Step 4
41. Ignition ªOFFº.
2. Raise the vehicle.
3. Disconnect the Bank 2 HO2S 2 electrical connector.
4. Using a test light connected to a known good ground
(do not use Bank 2 HO2S 2 heater ground or Bank 2
HO2S 2 low), probe the ignition feed circuit at the
Bank 2 HO2S 2 electrical connector (PCM harness
side).
Does the test light illuminate?
ÐGo to Step 5Go to Step 7
5Connect the test light between the Bank 2 HO2S 2
ignition feed and the Bank 2 HO2S 2 heater ground.
Does the test light illuminate?
ÐGo to Step 6Go to Step 8

6E±221
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
DTC P0161 ± HO2S Heater Circuit Bank 2 Sensor 2

 
StepNo Ye s Value(s) Action
61. Allow the HO2S to cool for at least 15 minutes.
2. Using a DVM, measure resistance between the
Bank 2 HO2S 2 ignition feed and the Bank 2 HO2S 2
heater ground at the Bank 2 HO2S 2 pigtail.
Is the HO2S resistance within the specified values?
3-6 ohmsGo to Step 9Go to Step 10
7Repair the open Bank 2 HO2S 2 ignition feed circuit to
Bank 2 HO2S 2.
Is the action complete?
ÐVerify repairÐ
8Repair the open Bank 2 HO2S 2 heater ground circuit.
Is the action complete?
ÐVerify repairÐ
91. Check for a poor connection at the Bank 2 HO2S 2
harness terminals.
2. If a poor connection is found, replace the terminals.
Was a poor connection found?
ÐVerify repairGo to Step 10
101. Ignition ªOFFº.
2. Disconnect the PCM and check the continuity of the
Bank 2 HO2S 2 signal circuit and the Bank 2 HO2S
2 low circuit.
3. If the Bank 2 HO2S 2 signal circuit or HO2S low
circuit measures over 5 ohms, repair the open or
poor connection as necessary.
Was a problem found?
ÐVerify repairGo to Step 11
111. Ignition ªOFFº.
2. Disconnect the PCM and check the continuity of the
Bank 2 HO2S 2 signal circuit and the Bank 2 HO2S
2 low circuit.
3. If the Bank 2 HO2S 2 signal circuit or HO2S low
circuit measures over 5 ohms, repair the open or
poor connection as necessary.
Was a problem found?
ÐVerify repairGo to Step 12
12Check for a poor Bank 2 HO2S 2 low circuit terminal
connection at the PCM and replace the terminal if
necessary.
Did the terminal require replacement?
ÐVerify repairGo to Step 13
13Check for a poor Bank 2 HO2S 2 high circuit terminal
connection at the PCM and replace the terminal if
necessary.
Did the terminal require replacement?
ÐVerify repairGo to Step 14
14Replace Bank 2 HO2S 2.
Is the action complete?
ÐVerify repairÐ
15Locate and repair the short to ground in the Bank 2
HO2S 2 ignition feed circuit and replace the faulty fuse.
Is the action complete?
ÐVerify repairÐ

6E±222
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P0171 Fuel Trim System Lean Bank 1
060R200054
Circuit Description
To provide the best possible combination of driveability,
fuel economy, and emission control, a ªclosed loopº
air/fuel metering system is used. While in ªclosed loopº,
the powertrain control module (PCM) monitors the Bank 1
HO2S 1 and Bank 2 HO2S 1 signals and adjusts fuel
delivery based upon the HO2S signal voltages. A change
made to fuel delivery will be indicated by the long and
short term fuel trim values which can be monitored with a
Tech 2. Ideal fuel trim values are around 0%; if the HO2S
signals are indicating a lean condition the PCM will add
fuel, resulting in fuel trim values above 0%. If a rich
condition is detected, the fuel trim values will be below
0%, indicating that the PCM is reducing the amount of fuel
delivered. If an excessively lean condition is detected on
Bank 1, the PCM will set DTC P0171.
The PCM's maximum authority to control long term fuel
trim allows a range between ±15% (automatic
transmission) or ±12% (manual transmission) and +20%.
The PCM monitors fuel trim under various engine
speed/load fuel trim cells before determining the status of
the fuel trim diagnostic.
Conditions for Setting the DTC

None of the following: EGR DTCs, HO2S DTCs,
(response, transition, open, low volts, no activity), MAF
DTCs, TP sensor DTCs, MAP DTCs, IAT DTCs,
canister purge DTCs, EVAP DTCs, injector circuit
DTCs, or misfire DTCs.
Engine coolant temperature is between 6
C (42.8
F)
and 105
C (221
F).

Intake air temperature is between ±40
C (±40
F) and
120
C (248
F).

Manifold absolute pressure is between 24 kPa and 99
kPa.

Throttle angle is steady below 95%.

Vehicle speed is below 136 km/h (85 mph).

Engine speed is between 400 and 6,000 RPM.

Barometric pressure is greater than 72.5 kPa.

Mass air flow is between 2 g/second and 200 g/second.

Ignition voltage is above 9.5 volts.

Fuel system is in ªclosed loopº.

Canister purge duty cycle is greater than 0% if on.
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 P0171 will clear after 40 consecutive
warm-up cycles have occurred without a fault.

6E±223
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS

DTC P0171 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:

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
Bank 1 HO2S 1 display on the Tech 2 while moving
connectors and wiring harnesses related to the engine
harness. 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. DTCs other than P0171 and P0174 may indicate a
condition present which may cause a lean condition.
If this is the case, repairing the condition which
caused the other DTC will most likely correct the
DTC P0171/P0174.
4. If the DTC P0171 test passes while the Failure
Records conditions are being duplicated, the lean
condition is intermittent. Refer to
Diagnostic Aids or
Symptoms for additional information on diagnosing
intermittent problems.