coolant temperature ISUZU AXIOM 2002 Service Workshop 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) 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 60
C (140
F).

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.
OR
Bank 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.

6E±188
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code(DTC)
P0140 HO2S Circuit Insufficient Activity Bank 1 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 1 HO2S 1
and the Bank 1 HO2S 2 heated oxygen sensors. The
Bank 1 HO2S 2 sensor produces an output signal which
indicates the amount of oxygen present in the exhaust
gas entering the three-way catalytic converter. The Bank
1 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 catalyst is operating efficiently, the
Bank 1 HO2S 1 signal will be far more active than that
produced by the Bank 1 HO2S 2 sensor. If the Bank 1
HO2S 2 signal voltage remains between 400 mV and
500 mV for an extended period of time, DTC P0140 will be
set. 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 tomaintain a sufficiently high temperature for accurate
exhaust oxygen content readings further from the engine.
Conditions for Setting the DTC

No related DTCs.

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

The engine has been running for over 5 seconds.

Oxygen sensor heater is functioning properly.

Engine is operating in ªclosed loopº

Bank 1 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 Cleaning 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 P0140 will clear after 40 consecutive
warm-up cycles have occurred without a fault.

DTC P0140 can be cleared by using the Tech 2 ªClear
Infoº function or by disconnecting the PCM battery
feed.

6E±191
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC)
P0141 HO2S Heater Circuit Bank 1 Sensor 2
060R200054
Circuit Description
Heated oxygen sensors are used to minimize the amount
of time required for closed loop 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
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 2 to become active, a DTC P0141
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 airflow = 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.

Bank 1 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 P0141 will clear after 40 consecutive
warm-up cycles have occurred without a fault.

DTC P0141 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:

6E±194
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC)
P0151 HO2S Circuit Low Voltage Bank 2 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 320 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 2 HO2S 1 voltage
remains excessively low for an extended period of time,
DTC P0151 will be set.
Conditions for Setting the DTC

No related DTCs.

The engine 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 2 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 P0151 will clear after 40 consecutive
warm-up cycles have occurred without a fault.

DTC P0151 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 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
P0151 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±197
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC)
P0152 HO2S Circuit High Voltage Bank 2 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 320 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 the injector
pulse width as necessary. If the Bank 2 HO2S 1 voltage
remains excessively high for an extended period of time,
DTC P0152 will be set.
Conditions for Setting the DTC

No related DTCs.

The engine is operating in ªclosed loopº.

The engine coolant temperature is above 60
C
(140
F).

Bank 2 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 2 HO2S 1 signal voltage remains above 500 mV
during deceleration fuel cutoff mode operation for up to
3 seconds.
Action Taken When the DTC Sets

The PCM will ªONº 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 P0152 will clear after 40 consecutive
warm-up cycles have occurred without a fault.

DTC P0152 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 ± 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
P0152 may be set. Refer to
Fuel System Diagnosis.

Rich injector(s) ± Perform ªInjector Balance Testº.

Leaking injector ± Refer to
Fuel System Diagnosis.

Evaporative emissions (EVAP) system ± Check the
canister for fuel saturation. If the canister is full of fuel,

6E±200
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC)
P0153 HO2S Slow Response Bank 2 Sensor 1
060R200054
Circuit Description
The powertrain control module (PCM) continuously
monitors the heated oxygen sensor (HO2S) activity for 90
seconds after ªclosed loopº has been enabled. During the
monitoring period the PCM counts the number of times
that a rich-to-lean and lean-to-rich response is indicated
and adds the amount of time it took to complete all
rich-to-lean transitions and lean-to-rich transitions. With
this information, an average time for rich-to-lean and
lean-to-rich transitions can be determined. If the average
response time of either transition is too slow, a DTC
P0153 will be set.
A lean-to-rich transition is indicated when the HO2S
voltage changes from less than 300 mV to greater than
600 mV. A rich-to-lean transition is indicated when the
HO2S voltage changes from more than 600 mV to less
than 300 mV. An HO2S that responds too slowly is likely
to be faulty and should be replaced.
Conditions for Setting the DTC

No related DTCs.

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

The engine is operating in ªclosed loopº.

Engine has been running for over 60 seconds.

Canister purge duty cycle is above 2%.

Engine speed is between 1500 RPM and 3000 RPM.
Mass air flow is between 18 g/second and 42 g/second.

All above conditions are met for 3 seconds.

90 seconds after ªclosed loopº has been enabled, Bank
2 HO2S 1 average transition time between 300 mV
and 600 mV is too slow. The lean-to-rich average
transition response time was longer than 94
milliseconds or the rich-to-lean average transition
response time was longer than 105 milliseconds.
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 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 P0153 will clear after 40 consecutive
warm-up cycles have occurred without a fault.

DTC P0153 can be cleared by using the Tech 2 ªClear
Infoº function or by disconnecting the PCM battery
feed.

6E±204
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC)
P0154 HO2S Circuit Insufficient Activity Bank 2 Sensor 1
060R200054
Circuit Description
The powertrain control module (PCM) supplies a bias
voltage of about 450 mV between the heated oxygen
sensor (HO2S) high 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 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 2 HO2S 1 voltage remains at or
near the 450 mV bias for an extended period of time, DTC
P0154 will be set, indicating an open sensor signal or
sensor low circuit.
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 for accurate exhaust oxygen
content readings further from the engine.
Conditions for Setting the DTC

No related DTCs.

Engine coolant temperature is above 60
C (140
F).
The engine has been running for over 5 seconds.

Oxygen sensor heater is functioning properly.

Bank 2 HO2S 1 signal voltage remains between
400 mV and 500 mV 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 P0154 will clear after 40 consecutive
warm-up cycles have occurred without a fault.

DTC P0154 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,

6E±207
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P0155
HO2S Heater Circuit Open Bank 2 Sensor 1
060R200054
Circuit Description
Heated oxygen sensors are used to minimize the amount
of time required for closed loop 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
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 2 HO2S 1 to become active, a DTC P0155
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 mass air flow (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.

Heater signal is below 0.1A.

Bank 1 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 P0155 will clear after 40 consecutive
warm-up cycles have occurred without a fault.

DTC P0155 can be cleared by using the Tech 2 ªClear
infoº function or by disconnecting the PCM battery
feed.

6E±210
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC)
P0157 HO2S Circuit Low Voltage 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 excessively low for an
extended period of time, DTC P0157 will be set.
Conditions for Setting the DTC

No related DTCs.

The engine 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 2 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.
OR

Bank 2 HO2S 2 signal voltage remains below 400 mV
during ªpower enrichmentº 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 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 P0157 will clear after 40 consecutive
warm-up cycles have occurred without a fault.

DTC P0157 can be cleared by using the Tech 2 ªClear
Infoº function or by disconnecting the PCM battery
feed.

6E±213
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC)
P0158 HO2S Circuit High Voltage 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 excessively high for an
extended period of time, DTC P0158 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 60
C (140
F).

Bank 2 HO2S 2 signal voltage remains above 952 mV
during normal ªclosed loopº operation for a total of 106
seconds over a 125-second period.
OR

Bank 2 HO2S 2 signal voltage remains above 500 mV
during deceleration fuel cutoff 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 P0158 will clear after 40 consecutive
warm-up cycles have occurred without a fault.

DTC P0158 can be cleared by using the Tech 2 ªClear
Infoº function or by disconnecting the PCM battery
feed.