ISUZU AXIOM 2002 Service Repair Manual

6E±314
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
DTC P0420 ± TWC System Low Efficiency Bank 1

StepActionValue(s)Ye sNo
1Was the ªOn-Board Diagnostic (OBD) System Checkº
performed?
ÐGo to Step 2
Go to OBD
System
Check
2Are any other DTCs set (such as P0140)?
Ð
Diagnose
other DTC(s)
first
Go to Step 3
31. Visually and physically inspect the three-way
catalytic converter for damage. Check for the
following:

dents

severe discoloration caused by excessive
temperatures

holes

internal rattle caused by damaged catalyst
2. Also, ensure that the three-way catalytic converter
is a proper original equipment manufacturer part.
Did your inspection reveal a problem?
ÐGo to Step 6Go to Step 4
41. Visually and physically inspect the exhaust system
between the three-way catalytic converter and the
rear converter flange for leaks, damage, and loose
or missing hardware.
2. If a problem is found, repair as necessary.
Did your inspection reveal a problem?
Ð
Go to Step 7
to verify
repair
Go to Step 5
51. Visually and physically inspect the Bank 1 HO2S 2.
2. Ensure that the Bank 1 HO2S 2 is secure and that
the pigtail and wiring harness is not contacting the
exhaust pipe or is not otherwise damaged.
3. If a problem is found, repair as necessary.
Did your inspection reveal a problem?
Ð
Go to Step 7
to verify
repair
Go to Step 6
6Replace the three-way catalytic converter.
NOTE: Check for conditions which may cause catalyst
damage (refer to
Diagnostic Aids).
Is the action complete?
Ð
Go to Step 7
to verify
repair
Ð
71. Review and record the Tech 2 Failure Records data.
2. Clear DTC P0420.
3. Start the engine and allow it to warm up until the
engine coolant temperature monitored on the Tech
2 is above the specified value.
4. Run the engine to maintain the specified mass air
flow range for at least 2 minutes.
5. Operate the vehicle to maintain DTC P0420 test
conditions (refer to
DTC Test Description in
Diagnostic Support for detailed instructions).
6. Using a Tech 2, monitor ªDTCº info for DTC P0420
until the DTC P0420 test runs.
7. Note the test result.
Does the Tech 2 indicate DTC P0420 passed this
ignition?
Engine
coolant temp:
greater than
60
C
(140
F).
Mass air flow:
between 8
g/second and
50 g/second
Complete
repair. If a
driveability
symptom still
exists, refer
to
Symptoms.
Go to the
Diagnostic
Aids

6E±315
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P0430 TWC System Low Efficiency Bank 2
T321075
Circuit Description
To control emissions of hydrocarbons (HC), carbon
monoxide (CO), and oxides of nitrogen (NOx), a
three-way catalyst (TWC) is used. The catalyst 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 PCM detects a level
of Bank 2 HO2S 2 activity that indicates the catalyst is no
longer operating efficiently, DTC P0430 will be set.
Conditions for Setting the DTC

No related DTCs.

The engine is operating in ªclosed loopº.

Engine air load is below 99%.

Engine coolant temperature is between 70
C (158
F)
and 120
C (248
F).
Mass air flow is between 2.5 g/second and 10
g/second.

Change in engine load is below 8%.

Engine speed is below 200 RPM.

Catalyst temperature is above 350
C (662
F).

The PCM determines that the catalyst's oxygen
storage capacity is below the acceptable threshold.

Intake air temperature is between ±20
C (4
F) and
70
C (158
F).

Throttle angle is less than 1.5%.

Barometric Pressure is more than 72 kPa.
Action Taken When the DTC Sets

The PCM will illuminate the malfunction indicator lamp
(MIL) the first time 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 P0430 will clear after 40 consecutive
warm-up cycles have occurred without a fault.

DTC P0430 can be cleared by using the Tech 2 ªClear
Infoº function or by disconnecting the PCM battery
feed.

6E±316
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.
7. Difficulty completing the DTC P0430 ªStatus This
Ignº, test may be encountered in areas where test
conditions cannot be maintained easily, especially in
urban areas. To minimize the amount of driving
required to complete the DTC P0430 ªStatus This
Ignº, test, use the following procedure:

Allow the engine to warm up completely.

With the vehicle in ªParkº, monitor mass air flow on
the Tech 2 and hold part throttle to maintain a
reading of over 12 g/second for at least 2 minutes.
This will achieve the ªwarm catalystº required for
running the test.

Operate the vehicle in second or third gear to remain
in the DTC P0430 test conditions described in
ªConditions for Setting the DTCº as much as
possible. If you must stop the vehicle, maintain the
ªwarm catalystº criteria as follows:
± Place the vehicle in ªParkº or ªNeutralº,
± Hold part throttle to maintain a mass air flow
reading of over 15 g/second for the duration of the
stop.
The ªTWC Monitor Test Counterº displayed on the Tech 2
may be used to monitor the progress of the TWC
diagnostic. To complete the TWC diagnostic with a good
catalyst, the counter must be allowed to increment to 49
samples and roll over to 0 at least twice.

6E±317
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
DTC P0430 ± TWC System Low Efficiency Bank 2

StepActionValue(s)Ye sNo
1Was the ªOn-Board Diagnostic (OBD) System Checkº
performed?
ÐGo to Step 2
Go to OBD
System
Check
2Are any other DTCs set (such as P0160)?
Ð
Diagnose
other DTC(s)
first
Go to Step 3
31. Visually and physically inspect the three-way
catalytic converter for damage. Check for the
following:

dents

severe discoloration caused by excessive
temperatures

holes

internal rattle caused by damaged catalyst
2. Also, ensure that the three-way catalytic converter
is a proper original equipment manufacturer part.
Did your inspection reveal a problem?
ÐGo to Step 6Go to Step 4
41. Visually and physically inspect the exhaust system
between the three-way catalytic converter and the
rear converter flange for leaks, damage, and loose
or missing hardware.
2. If a problem is found, repair as necessary.
Did your inspection reveal a problem?
Ð
Go to Step 7
to verify
repair
Go to Step 5
51. Visually and physically inspect the Bank 2 HO2S 2.
2. Ensure that the Bank 2 HO2S 2 is secure and that
the pigtail and wiring harness is not contacting the
exhaust pipe or is not otherwise damaged.
3. If a problem is found, repair as necessary.
Did your inspection reveal a problem?
Ð
Go to Step 7
to verify
repair
Go to Step 6
6Replace the three-way catalytic converter.
NOTE: Check for conditions which may cause catalyst
damage (refer to
Diagnostic Aids).
Is the action complete?
Ð
Go to Step 7
to verify
repair
Ð
71. Review and record the Tech 2 Failure Records data.
2. Clear DTC P0430.
3. Start the engine and allow it to warm up until the
engine coolant temperature monitored on the Tech
2 is above the specified value.
4. Run the engine to maintain the specified mass air
flow range for at least 6 minutes.
5. Operate the vehicle to maintain DTC P0430 test
conditions (refer to
DTC Test Description in
Diagnostic Support for detailed instructions).
6. Using a Tech 2, monitor ªDTCº info for DTC P0430
until the DTC P0430 test runs.
7. Note the test result.
Does the Tech 2 indicate DTC P0430 passed this
ignition?
Engine
coolant temp:
greater than
70
C
(158
F).
Mass air flow:
between 2.5
g/second and
10 g/second
Complete
repair. If a
driveability
symptom still
exists, refer
to
Symptoms.
Go to the
Diagnostic
Aids

6E±318
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P0440 EVAP System
060RY00398
Circuit Description
The evaporative system includes the following
components:

Fuel tank

EVAP canister purge duty solenoid valve

Fuel tank (vapor) pressure sensor

Fuel pipes and hoses

Vapor lines

Fuel cap

Evaporative emissions canister

Purge lines

EVAP canister vent valve (purge solenoid)
The evaporative leak detection diagnostic strategy is
based on applying vacuum to the EVAP system and
monitoring vacuum decay. The powertrain control
module (PCM) monitors vacuum level via the fuel tank
pressure sensor input. At an appropriate time, the EVAP
canister purge solenoid and the EVAP canister vent
solenoid are turned ªONº, allowing engine vacuum to
draw a small vacuum on the entire evaporative emissions
system. If a sufficient vacuum level cannot be achieved, a
large leak or a faulty EVAP canister purge solenoid is
indicated. This can be caused by the following conditions:

Disconnected or faulty fuel tank pressure sensor

Missing or faulty fuel cap

Disconnected, damaged, pinched, or blocked EVAP
purge line

Disconnected or damaged EVAP vent hose
Disconnected, damaged, pinched, or blocked fuel tank
vapor line

Disconnected or faulty EVAP canister duty solenoid

Open ignition feed circuit to the EVAP canister vent
solenoid

Damaged EVAP canister

Leaking fuel sender assembly O-ring

Leaking fuel tank or fuel filler neck
Any of the above conditions can set DTC P0440.
Conditions for Setting the DTC

No TP sensor, IAT sensor, ECT sensor, or MAP sensor
DTCs set.

Start-up engine coolant temperature is less than 32
C
(90
F).

Start-up engine coolant temperature is not more than
7
C (13
F) greater than start-up intake air
temperature.

Start-up intake air temperature is greater than 4
C
(39
F) .

Start-up intake air temperature is not more than 2
C
(4
F) greater than start-up engine coolant
temperature.

Vehicle speed is less than 5 mph (8 km/h).

Throttle position is greater than 3%.

Minimal fuel slosh.

BARO is greater than 70 kPa.

The EVAP system is unable to achieve or maintain
vacuum during the diagnostic test.

6E±319
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS

Engine speed is less than 1200 RPM.

Above conditions are present for 60 to 180 seconds.
Action Taken When the DTC Sets

The PCM will ON the MIL after second trip with
detected the 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 when the diagnostic
has been run and the fault condition is no longer
present.

A history DTC P0440 will clear after 40 consecutive
warm-up cycles have occurred without a fault.

DTC P0440 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:

Cracked or punctured EVAP canister.

Damaged or disconnected source vacuum line, EVAP
purge line, vent hose or fuel tank vapor line.

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 to the
EVAP canister vent solenoid, EVAP canister purge
solenoid and the fuel tank pressure sensor for an
intermittent open or short circuit.

Kinked, pinched, or plugged vacuum source, EVAP
purge, or fuel tank vapor line±Verify that the lines are
not restricted.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. If an EVAP canister vent solenoid or an EVAP
canister purge solenoid electrical fault is present,
the purge system will not operate correctly.
Repairing the electrical fault will very likely correct
the condition that set DTC P0440.
3. Checks the fuel tank pressure sensor at ambient
pressure.
4. Determines whether or not the EVAP system can be
sealed sufficiently to be pressurized. If not, the
large leak must be located and corrected before
continuing with diagnosis.
5. Verifies that the fuel tank pressure sensor accurately
reacts to EVAP system pressure changes.
8. Checks for a blocked EVAP canister purge solenoid.
The PCM commands the EVAP canister purge
solenoid ªOFFº (open) and the vent solenoid ªONº
(closed) with the Tech 2 ªSystem Perfº, EVAP
output control function activated. Any pressure in
the system should be released through the EVAP
canister purge solenoid within a few seconds when
ªSystem Perfº, is activated.
9. Ensures that sufficient source vacuum is present at
the EVAP canister purge solenoid.
DTC P0440 ± EVAP System

StepActionValue(s)Ye sNo
1Was the ªOn-Board Diagnostic (OBD) System Checkº
performed?
ÐGo to Step 2
Go to OBD
System
Check
2Is DTC P0452 or P0453 also set?
Ð
Go to other
DTC first
Go to Step 3
31. Ignition ªOFFº.
2. Remove the fuel cap.
3. Ignition ªONº.
4. Observe ªFuel Tank Pressureº on the Tech 2.
Does the Tech 2 indicate ªFuel Tank Pressureº at the
specified value?
1.51 VGo to Step 4
Go to DTC
P0452
or
DTC P0453
41. Replace the fuel cap.
2. Engine is running.
3. Observe ªFuel Tank Vacuumº on the Tech 2.
Does Tech 2 indicate ªFuel Tank Vacuumº at the
specified value?
1.47±1.51 VGo to Step 7Go to Step 6

6E±320
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
DTC P0440 ± EVAP System

 
StepNo Ye s Value(s) Action
5Ignition ªOFFº.
1. Disconnect the fuel tank vapor line and the EVAP
purge line from the EVAP canister.
2. Block the canister fitting for the fuel tank vapor line.
3. Connect a hand vacuum pump to the canister fitting
for the EVAP purge line.
4. Ensure that the EVAP canister vent solenoid is still
commanded ªONº (closed).
5. Attempt to apply vacuum to the EVAP canister.
Observe ªFuel tank pressureº on the Tech 2.
Does the Tech 2 indicate ªFuel tank pressureº at the
specified value?
1.47±1.51 VGo to Step 8Go to Step 7
61. Visually/physically check for the following
conditions:

Restricted fuel tank vapor line.

Restricted EVAP purge line.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repair
Go to DTC
P0452
or
DTC P0453
71. Visually/physically check for the following
conditions:

Vent hose disconnected or the damaged.

EVAP canister damaged.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 11
81. Visually/physically check for the following
conditions:

Missing or faulty fuel cap.

Disconnected or leaking fuel tank vapor line.

Disconnected or damaged EVAP purge line.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 9
9Replace the EVAP canister purge solenoid.
Is the action complete?
ÐVerify repairÐ
10Locate and repair cause of no source vacuum to the
EVAP canister purge solenoid.
Is the action complete?
ÐVerify repairÐ
11Replace the EVAP canister vent solenoid.
Is the action complete?
ÐVerify repairÐ

6E±321
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P0442 EVAP System Small Leak Detected
060RY00398
Circuit Description
The evaporative system includes the following
components:

Fuel tank

EVAP canister vent solenoid

Fuel tank (vapor) pressure sensor

Fuel pipes and hoses

Vapor lines

Fuel cap

Evaporative emissions canister

Purge lines

EVAP canister purge solenoid
The evaporative leak detection diagnostic strategy is
based on applying vacuum to the EVAP system and
monitoring vacuum decay. The powertrain control
module (PCM) monitors vacuum level via the fuel tank
pressure sensor input. At an appropriate time, the EVAP
canister purge solenoid and the EVAP canister vent
solenoid are turned ªONº, allowing engine vacuum to
draw a small vacuum on the entire evaporative emissions
system. After the desired vacuum level has been
achieved, the EVAP canister purge solenoid is turned
ªOFFº, sealing the system. A leak is detected by
monitoring for a decrease in vacuum level over a given
time period, all other variables remaining constant. A
small leak in the system will cause DTC P0442 to be set.
Conditions for Setting the DTC

No TP sensor, ECT sensor, Tank pressure sensor, IAT
sensor, or MAP sensor DTCs set.

BARO is more than 70 kPa.

Engine speed is less than 1200 RPM.

Fuel level is between 15% and 85%.

Vehicle speed is less than 5 mph (8 km/h).

The DTC P0440 diagnostic test has passed.

A vacuum decay condition, indicating a small leak, is
detected during the diagnostic test.
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 P0442 will clear after 40 consecutive
warm-up cycles have occurred without a fault.

DTC P0442 can be cleared by using the Tech 2 ªClear
Infoº function or by disconnecting the PCM battery
feed.

6E±322
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Aids
Check for the following conditions:

Cracked or punctured EVAP canister.

Damaged source vacuum line, EVAP purge line, EVAP
vent hose or fuel tank vapor line.

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 to the
EVAP canister vent solenoid, EVAP canister purge
solenoid and the fuel tank pressure sensor for an
intermittent open or short circuit.
Reviewing the Failure Records vehicle mileage since the
diagnostic test last failed may help determine how oftenthe 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. If an EVAP canister vent solenoid or an EVAP
canister purge solenoid electrical fault is present,
the purge system will not operate correctly.
Repairing the electrical fault will very likely correct
the condition that set DTC P0442.
3. Checks the fuel tank pressure sensor at ambient
pressure.
4. Verifies that the fuel tank pressure sensor accurately
reacts to EVAP system pressure changes.
DTC P0442 ± EVAP System Leak Detected

StepActionValue(s)Ye sNo
1Was the ªOn-Board Diagnostic (OBD) System Checkº
performed?
ÐGo to Step 2
Go to OBD
System
Check
21. Ignition ªOFFº.
2. Remove the fuel cap.
3. Ignition ªONº.
4. Observe ªFuel Tank Pressureº on the Tech 2.
Does the Tech 2 indicate ªFuel Tank Pressureº at the
specified value?
1.51VGo to Step 3
Go to Fuel
Tank
Pressure
System
3IMPORTANT:Before continuing with diagnosis, zero
the EVAP pressure and vacuum gauges on EVAP
pressure/purge cart J 41413 (refer to tool operating
instructions).
1. Replace the fuel cap.
2. Capture Failure Records data for DTC P0442 and
clear DTCs.
3. Connect the EVAP pressure/purge cart J 41413 to
the EVAP service port.
4. Using the Tech 2, command the EVAP canister vent
solenoid ªONº (closed).
5. Using the EVAP pressure/purge cart J 41413,
pressurize the EVAP system to the specified value.
6. Observe ªFuel Tank Pressureº on the Tech 2.
Does the Tech 2 indicate ªFuel Tank Pressureº at the
specified value?
1.47VGo to Step 4
Go to Fuel
Tank
Pressure
System
41. Ignition ªONº, engine idling.
2. Using the Tech 2, command the EVAP canister vent
solenoid ªONº (closed).
3. Using the EVAP pressure/purge cart J 41413,
pressurize the EVAP system to 15 in. H
2O.
4. Switch the rotary switch on the cart to ªHOLDº and
observe the EVAP pressure gauge.
Does the pressure decrease to less than the specified
value within 2 minutes?
1.47 ± 1.51VGo to Step 5
Refer to
Diagnostic
Aids

6E±323
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
DTC P0442 ± EVAP System Leak Detected

 
StepNo Ye s Value(s) Action
51. Disconnect the fuel tank vapor line and the EVAP
purge line from the EVAP canister.
2. Block the canister fitting for the fuel tank vapor line.
3. Connect a hand vacuum pump to the canister fitting
for the EVAP purge line.
4. Ensure that the EVAP canister vent solenoid is still
commanded ªONº (closed).
5. Attempt to apply vacuum to the EVAP canister.
Can the vacuum be maintained at the specific value?
1.46VGo to Step 8Go to Step 6
61. Visually/physically check for the following
conditions:

Vent hose disconnected or damaged.

EVAP canister damaged.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐGo to Step 10Go to Step 7
7Replace the EVAP canister vent solenoid.
Is the action complete?
ÐGo to Step 10Ð
81. Visually/physically check for the following
conditions:

Missing or faulty fuel cap.

Disconnected or leaking fuel tank vapor line.

Disconnected or damaged EVAP purge line.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐGo to Step 10Go to Step 9
91. Using Tech 2, command the EVAP canister vent
solenoid ªONº (closed).
2. With the cart connected to the EVAP service port,
continuously attempt to pressurize the EVAP
system by leaving the cart control knob in the
pressurize position.
3. Using ultrasonic leak detector J 41416, locate and
repair leak in EVAP system. (It may be necessary to
partially lower the fuel tank to examine the
connections on top of the tank.)
Is the action complete?
ÐGo to Step 10Ð
101. Ignition ªONº, engine not running.
2. Using the Tech 2, command the EVAP canister vent
solenoid ªONº (closed).
3. Using the EVAP pressure/purge cart J 41413,
pressurize and monitor the EVAP system to 15 in.
H
2O.
4. Switch the rotary switch on the cart to ªHOLDº and
observe the EVAP pressure gauge.
Does the pressure decrease to less than the specified
value within 2 minutes?
2.14VGo to Step 2Verify repair