oxygen sensor DAEWOO LACETTI 2004 Service Workshop Manual

1F – 376IENGINE CONTROLS
DAEWOO V–121 BL4
S A history DTC will clear after 40 consecutive warm–
up cycles without a fault.
S The DTC(s) can be cleared by using the scan tool.
S Disconnecting the ECM battery feed for more than
10 seconds.
Diagnostic Aids
The DTC P0132 or rich exhaust is most likely caused by
one of the following items:
S Fuel pressure – The system will go rich if the fuel
pressure is too high. The ECM can compensate for
some increase, but if it gets too high, a DTC P0132
will be set
S Leaking injector – A leaking or malfunctioning injec-
tor can cause the system to go rich causing a DTC
P0132.
S Manifold Absolute Pressure (MAP) sensor – An
output that causes the ECM to sense a higher than
normal manifold pressure (low vacuum) can cause
the system to go rich. Disconnecting the MAP sen-
sor will allow the ECM to substitute a fixed value for
the MAP sensor. Substitute a different a MAP sen-
sor, if the rich condition is gone while the sensor is
disconnected.
S Pressure regulator – Check for a leaking fuel pres-
sure regulator diaphragm by checking for the pres-
ence of liquid fuel in the vacuum line to the regula-
tor.
S TP sensor – An intermittent TP sensor output will
cause the system to go rich due to a false indica-
tion of the engine accelerating.
S HO2S1 contamination – Inspect the HO2S1 for sili-
cone contamination from fuel or the use of improper
Room Temperature Vulcanizing sealant. The sensormay have a white powdery coating which may re-
sult in a high but false voltage signal (rich exhaust
indication). The ECM will then reduce the amount
of fuel delivered to the engine, causing a severe
surge or driveability problem.
Test Description
Number(s) below refer to the step number(s) on the Diag-
nostic Table.
1. The On–Board Diagnostic (EOBD) System Check
prompts the technician to complete some basic
checks and store the freeze frame and failure re-
cords data on the scan tool if applicable. This
creates an electronic copy of the data taken when
the malfunction occurred. The information is then
stored on the scan tool for later reference.
2. This step determines if DTC P0132 is the result of
a hard failure or an intermittent condition. It may be
necessary to operate the vehicle within the Freeze
Frame conditions and Conditions for Setting the
DTC in order to duplicate the malfunction detected
by the ECM.
4. This step simulates a DTC P0131. If the ECM
senses the change, the ECM and the wiring are
OK.
6. The replacement ECM must be reprogrammed.
Refer to the latest Techline procedure for ECM re-
programming.
8. If no malfunctions have been found at this point and
no additional DTCs were set, refer to ”Diagnostic
Aids” in this section for additional checks and infor-
mation.
DTC P0132 – Front Heated Oxygen Sensor (HO2S1) High Voltage
StepActionValue(s)YesNo
1Perform an On–Board Diagnostic (EOBD) System
Check.
Was the check performed?–Go to Step 2Go to
”On–Board
Diagnostic Sys-
tem Check”
21. Install a scan tool to the Data Link Connector
(DLC).
2. Start the engine and idle at normal operating
temperature.
Does the Front Heated Oxygen Sensor (HO2S1)
voltage remain below the value specified?952 mVGo to Step 4Go to Step 3
31. Review the Freeze Frame data and note the
parameters.
2. Operate the vehicle within the Freeze frame
conditions and Conditions For Setting the DTC
as noted.
Does the HO2S1 voltage stay below the specified
value?952 mVGo to Step 4Go to Step 7

1F – 378IENGINE CONTROLS
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P0133
FRONT HEATED OXYGEN SENSOR (HO2S1) SLOW
RESPONSE
Circuit Description
The Engine Control Module (ECM) continuously monitors
the Front Heated Oxygen Sensor (HO2S1) activity for 100
seconds. During the monitor period, the ECM counts the
number of times that the HO2S1 switches from rich to lean
and from lean to rich and adds the amount of time it took
to complete all switches. With this information, an average
time for all switches can be determined. If the average time
to switch is too out of specification, a DTC P0133 will set.
If the HO2S1 pigtail wiring, connector, or terminal is dam-
aged, the entire HO2S1 assembly must be replaced. Do
not attempt to repair the wiring, connector, or terminals. In
order for the sensor to function properly, it must have a
clean air reference provided to it. This clean air reference
is obtained by way of the HO2S1 wire(s). Any attempt to
repair the wires, connector, or terminals could result in the
obstruction of the air reference and degrade HO2S1 per-
formance.
Conditions for Setting the DTCS HO2S1 average transition time between 0.3–0.6
volts, lean to rich is greater than 156 millisec-
onds(A/T) or rich to lean is greater than 140 milli-
seconds (M/T).
S Closed loop stoichiometry.
S Engine Coolant Temperature (ECT) is greater than
70°C (158°F).
S System voltage is greater than 10 volts.
S Engine run time is greater than 60 seconds.
S Purge Duty Cycle (DC) is less than 20%.
S The rpm is between 1600 and 4300.
S Airflow is between 9 and 40 g/sec.
S DTCs P0106, P0107, P0108, P0117, P0118,
P0122, P0123, P0131, P0132, P0134, P0135,
P1167, P0171, P1171, P0172, P0201, P0202,
P0203, P0204, P0300, P0336, P0337, P0351,
P0352, P0402, P0404, P0405, P0406, P0506,
P0507, P1404, and P0443 are not set.
S 2 second delay after conditions are met.
Action Taken When the DTC Sets
S The Malfunction Indicator Lamp (MIL) will illuminate
after three consecutive ignition cycle with a fail.

ENGINE CONTROLS 1F – 379
DAEWOO V–121 BL4
S The ECM will record operating conditions at the
time the diagnostic fails. This information will be
stored in the Freeze Frame and Failure Records
buffers.
S A history DTC is stored.
Conditions for Clearing the MIL/DTC
S The MIL will turn off after four consecutive ignition
cycles in which the diagnostic runs without a fault.
S A history DTC will clear after 40 consecutive warm–
up cycles without a fault.
S The DTC(s) can be cleared by using the scan tool.
S Disconnecting the ECM battery feed for more than
10 seconds.
Diagnostic Aids
DTC P0133 or slow response is most likely caused by one
of the following items:
S Fuel pressure – The system will go rich if fuel pres-
sure is too high. The ECM can compensate for
some increase, but if it gets too high, a DTC P0133
may set. Refer to”Fuel System Diagnosis” in this
section.
S Leaking injector – A leaking or malfunctioning injec-
tor can cause the system to go rich.
S Manifold Absolute Pressure (MAP) sensor – An
output that causes the ECM to sense a higher than
normal manifold pressure (low vacuum) can cause
the system to go rich. Disconnecting the MAP sen-
sor will allow the ECM to set a fixed value for the
MAP sensor. Substitute a different MAP sensor if
the rich condition is gone while the sensor is dis-
connected.S Pressure regulator – Check for a leaking fuel pres-
sure regulator diaphragm by checking for the pres-
ence of liquid fuel in the vacuum line to the pres-
sure regulator.
S Throttle Position (TP) sensor – An intermittent TP
sensor output can cause the system to go rich due
to a false indication of the engine accelerating.
S HO2S1 contamination – Inspect HO2S1 for silicone
contamination from fuel or use of improper room
temperature vulcanizing (RTV) sealant. The sensor
may have a white powdery coating, resulting in a
high but false voltage signal (rich exhaust indica-
tion). The ECM will then reduce the amount of fuel
delivered to the engine causing a severe surge or
driveability problem.
Test Description
Number(s) below refer to the step number(s) on the Diag-
nostic Table.
1. The On–Board Diagnostic (EOBD) System Check
prompts the technician to complete some basic
checks and store the freeze frame and failure re-
cords data on the scan tool if applicable. This
creates an electronic copy of the data taken when
the malfunction occurred. The information is then
stored on the scan tool for later reference.
14. The replacement ECM must be reprogrammed.
Refer to the latest Techline procedure for ECM re-
programming.
17. If no malfunctions have been found at this point and
no additional DTCs were set, refer to ”Diagnostic
Aids” for additional checks and information.
DTC P0133 – Front Heated Oxygen Sensor (HO2S1) Slow
Response
StepActionValue(s)YesNo
1Perform an On–Board Diagnostic (EOBD) System
Check.
Was the check performed?–Go to Step 2Go to
”On–Board
Diagnostic Sys-
tem Check”
21. Install a scan tool to the Data Link Connector
DLC).
2. Turn the ignition ON.
Are any additional Diagnostic Trouble Codes
(DTCs) set?–Go to
”Applicable
DTC table”Go to Step 3
31. Start the engine and idle at normal operating
temperature.
2. Operate the vehicle within the specified param-
eter under the Conditions For Setting the DTC.
3. Using the scan tool monitor the specific DTC
information for DTC P0133 until DTC P0133
test run.
Does the scan tool indicate DTC P0133 failed this
ignition cycle?–Go to Step 4Go to
”Diagnostic
Aids”

1F – 380IENGINE CONTROLS
DAEWOO V–121 BL4
StepNo Yes Value(s) Action
4Did the scan tool indicate that DTC P1133 or P1134
failed this ignition cycle.–Go to
”Applicable
DTC table”Go to Step 5
5Check the exhaust manifold/catalytic converter for
a leak and repair as needed.
Is the repair complete?–Go to Step 16Go to Step 6
6Visually/physically inspect for the following items:
S Front Heated Oxygen Sensor (HO2S1) is se-
curely installed.
S Corrosion on the terminals.
S Terminal tension.
S HO2S1 wiring harness for poor terminal con-
nection or damaged wiring.
Is a problem found in any of the above areas?–Go to Step 9Go to Step 7
71. Turn the ignition OFF.
2. Disconnect the HO2S1 connector.
3. Jumper the HO2S1 low circuit, terminal 3 to
ground.
4. Turn the ignition ON.
Does the scan tool indicate the voltage between the
specified value?400 – 500 mVGo to Step 8Go to Step 10
8Jumper the HO2S1 signal and low circuit terminal 4
to ground.
Does the scan tool indicate the voltage below the
specified value?200 mVGo to Step 15Go to Step 13
9Repair the condition as necessary.
Is the repair complete?–Go to Step 16–
10S Turn the ignition OFF.
S Disconnect the ECM connector.
S Check the HO2S1 low circuit for an open or
poor connection and repair as needed.
Is the repair complete?–Go to Step 16Go to Step 11
11Check the terminal M29 of the ECM for poor connec-
tion and repair as needed.
Is the repair complete?–Go to Step 16Go to Step 14
12Check the HO2S1 signal circuit for an open or short
to ground and repair as needed.
Is the repair complete?–Go to Step 16Go to Step 13
13Check the terminal M12 of the ECM for poor connec-
tion and repair as needed.
Is the repair complete?–Go to Step 16Go to Step 14
14S Turn the ignition OFF.
S Replace the ECM.
Is the repair complete?–Go to Step 16–
15Replace the HO2S1.
Is the repair complete?–Go to Step 16–

1F – 382IENGINE CONTROLS
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P0134
FRONT HEATED OXYGEN SENSOR (HO2S1) NO
ACTIVITY OR OPEN
Circuit Description
The Engine Control Module (ECM) supplies a voltage of
about 0.45 volts between terminals M12 and M29 (if mea-
sured with a 10 megohm digital voltmeter, this may read
as low as 0.32 volts). The Front Heated Oxygen Sensor
(HO2S1) varies the voltage within a range of about 1 volt
if the exhaust is rich, down through about 0.10 volts if the
exhaust is lean.
The sensor is like and open circuit and produces no volt-
age when it is below 315 °C (600 °F). An open sensor cir-
cuit or cold sensor causes Open Loop operation.
If the HO2S1 pigtail wiring, connector, or terminal is dam-
aged, the entire HO2S1 assembly must be replaced. Do
not attempt to repair the wiring, connector, or terminals. In
order for the sensor to function properly, it must have a
clean air reference provided to it. This clean air reference
is obtained by way of the HO2S1 wire(s). Any attempt to
repair the wires, connector or terminals could result in the
obstruction of the air reference and degrade the HO2S1
performance. Refer to”Front Heated Oxygen Sensor
(HO2S1)” in this section.Conditions for Setting the DTC
S HO2S1 voltage is between 420 and 480 mV.
S Engine Coolant Temperature (ECT) is greater than
60 °C (140 °F)
S System voltage is greater than 10 volts.
S Engine run time is greater than 60 seconds.
S Airflow is greater than 8 g/sec.
S DTCs P0106, P0107, P0108, P0117, P0118,
P0122, P0123, P0171, P0172, P0201, P0202,
P0203, P0204, P0300, P0336, P0337, P0351,
P0352, P0402, P0404, P0405, P0406, P0506,
P0507, P1404, and P0443 are not set.
S 3 second delay after exiting Decel Fuel Cut–off
(DFCO) mode.
Action Taken When the DTC Sets
S The Malfunction Indicator Lamp (MIL) will illumi-
nate.
S The ECM will record operating conditions at the
time the diagnostic fails. This information will be
stored in the Freeze Frame and Failure Records
buffers.
S A history DTC is stored.
S The vehicle will operate in Open Loop.

ENGINE CONTROLS 1F – 383
DAEWOO V–121 BL4
Conditions for Clearing the MIL/DTC
S The MIL will turn off after four consecutive ignition
cycles in which the diagnostic runs without a fault.
S A history DTC will clear after 40 consecutive warm–
up cycles without a fault.
S The DTC(s) can be cleared by using the scan tool.
S Disconnecting the ECM battery feed for more than
10 seconds.
Diagnostic Aids
S Normal scan tool voltage varies from 150 mV to
850 mV while in Closed Loop. If DTC P0134 is in-
termittent, refer to ”Intermittents” in this section.
Test Description
Number(s) below refer to the step number(s) on the Diag-
nostic Table.
1. The On–Board Diagnostic (EOBD) System Check
prompts the technician to complete some basic
checks and store the freeze frame and failure re-cords data on the scan tool if applicable. This
creates an electronic copy of the data taken when
the malfunction occurred. The information is then
stored on the scan tool for later reference.
2. During engine warm–up, the HO2S1 should warm
up, and its voltage output should vary between 150
mv and 850 mv. When the HO2S1 voltage varies,
the engine will go into Closed Loop. This deter-
mines if the HO2S1 1 is operating properly.
4. This will determine if the sensor is malfunctioning or
if the wiring or the ECM is the cause of the DTC
P0134.
6. Use only a high impedance digital voltmeter (DVM)
for this test. The test checks the continuity of the
HO2S1 signal and the ground circuits; if the ground
circuit is open, the ECM voltage on the circuit will
be over 0.6 volts (600 mv).
10. The replacement ECM must be reprogrammed.
Refer to the latest Techline procedure for ECM re-
programming.
DTC P0134 – Front Heated Oxygen Sensor (HO2S1)No Activity or
Open
StepActionValue(s)YesNo
1Perform an On–Board Diagnostic (EOBD) System
Check.
Was the check performed?–Go to Step 2Go to
”On–Board
Diagnostic Sys-
tem Check”
21. Install a scan tool to the Data Link Connector
(DLC).
2. Start the engine and idle at normal operating
temperature.
3. Operate the engine above the specified rpm for
2 minutes.
Does the scan tool indicate Closed Loop?80°C(176°F)
1200 rpmGo to Step 3Go to Step 4
31. Review the Freeze Frame data and note the
parameters.
2. Operate the vehicle within the Freeze frame
conditions and Conditions For Setting the DTC
as noted.
Does the scan tool indicate CLOSED LOOP?–Go to Step 12Go to Step 4
41. Turn the ignition OFF.
2. Disconnect HO2S1 connector.
3. Jumper the terminal 3 of HO2S1 connector and
ground.
4. Turn the ignition ON.
Does the scan tool indicate the HO2S1 voltage with-
in the specified value?400 – 500 mVGo to Step 5Go to Step 8
5Check the HO2S1 harness connector for malfunc-
tion or poor connection and repair as needed.
Is the repair complete?–Go to Step 12Go to Step 6

ENGINE CONTROLS 1F – 385
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P0135
FRONT HEATED OXYGEN SENSOR (HO2S1) HEATER
CIRCUIT NOT FUNCTIONING
Circuit Description
Heated oxygen sensors (HO2S) are used for fuel control
and post catalyst monitoring. Each HO2S compares the
oxygen content of the surrounding air with the oxygen con-
tent in the exhaust stream. The HO2S must reach operat-
ing temperature to provide an accurate voltage signal. A
heating element inside the HO2S minmizes the time re-
quired for the sensor to reach operating temperature. Volt-
age is provided to the heater by the ignition 1 voltage cir-
cuit through a fuse. With the engine running, ground is
provided to the heater by the HO2S heater low control cir-
cuit, through a low side driver within the engine control
module (ECM). The ECM monitors the current flow
through the heater for diagnosis.
If the ECM detects that the HO2S heater current is above
or blelow a specified range, DTC P0135 seats.
Conditions for Setting the DTC
S DTCs P0106, P0117, P0118, P1017 are not set.
S Engine run time is greater than 200 seconds.
S Filtered O2 heater current is less than 0.025 amps.
Action Taken When the DTC SetsS The Malfunction Indicator Lamp (MIL) will illuminate
after three consecutive ignition cycle with a fail.
S The ECM will record operating conditions at the
time the diagnostic fails. This information will be
stored in the Freeze Frame and Failure Records
buffers.
S A history Diagnostic Trouble Code (DTC) is stored.
Conditions for Clearing the MIL/DTC
S The MIL will turn off after three consecutive ignition
cycles in which the diagnostic runs without a fault.
S A history DTC will clear after 40 consecutive warm–
up cycles without a fault.
S DTC(s) can be cleared by using the scan tool.
Diagnostic Aids
An intermittent may be caused by rubbed through wire in-
sulation or a wire contacting the exhaust.
Check for poor connection or damaged harness – inspect
harness connectors for the following conditions:
S Improper mating
S Broken locks
S Improperly formed
S Damaged terminals
S Poor terminal–to–wire connection

1F – 386IENGINE CONTROLS
DAEWOO V–121 BL4
S Damaged harness
Test Description
Number(s) below refer to the step number(s) on the Diag-
nostic Table.
1. The On–Board Diagnostic (EOBD) System Check
prompts the technician to complete some basic
checks and store the freeze frame and failure re-
cords data on the scan tool if applicable. This
creates an electronic copy of the data taken when
the malfunction occurred. The information is then
stored on the scan tool for later reference.
2. This step determines if DTC P0135 is the result of
a hard failure or an intermittent condition. With the
ignition ON, engine OFF, the HO2S1 voltage dis-played on the scan tool should change within sever-
al minutes toward 0 or 1 volt, indicating that the
heater is working properly.
3. Probing terminal 2 of the HO2S1 connector verifies
if voltage is available to the HO2S1 heater.
4. If voltage is available at the connector, than it be-
comes a good voltage source to check for a ground
at terminal 3.
5. Determines if voltage is not available at the HO2S1
due to an open in the HO2S1 fuse or open ignition
feed circuit. If the fuse is open, determine if it was
due to a short in the ignition feed circuit before re-
placing the fuse.
DTC P0135 – Front Heated Oxygen Sensor (HO2S1) Heater Circuit
Not Functioning
StepActionValue(s)YesNo
1Perform an On–Board Diagnostic (EOBD) System
Check.
Is the check complete?–Go to Step 2Go to
”On–Board
Diagnostic Sys-
tem Check”
2Notice : If the engine has just been operating, allow
the engine to cool for about one–half hour before
proceeding.
1. Turn the ignition switch ON, with the engine
OFF.
2. Install a scan tool.
Does the Front Heated Oxygen Sensor (HO2S1)
voltage gradually change toward the specified volt-
age?0 v or 1 vGo to Step 13Go to Step 3
31. Disconnect the HO2S1 electrical connector.
2. With a test light connected to ground, probe
the ignition feed circuit, terminal 4 of the con-
nector.
Does the test light illuminate?–Go to Step 4Go to Step 5
4Connect a test light between the ignition feed and
ground circuits, terminal 4 and 3 of the connector.
Does the test light illuminate?–Go to Step 6Go to Step 7
5Inspect the fuse in the engine fuse block.
Is the fuse open?–Go to Step 8Go to Step 9
6Check the connections terminal 4 and 1 at the
HO2S1 connector and repair as necessary.
Is a repair necessary?–Go to Step 13Go to Step 10
7Check the connections terminal 3 at the HO2S1 con-
nector and repair as necessary.
Is a repair necessary?–Go to Step 13Go to Step 11
81. Check for a short to ground in the HO2S1 igni-
tion feed circuit and repair as necessary?
2. Replace open fuse.
Is the action complete?–Go to Step 13–

1F – 388IENGINE CONTROLS
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P0137
REAR HEATED OXYGEN SENSOR (HO2S2) LOW
VOLTAGE
Circuit Description
In order to control emissions, a catalytic converter is used
to convert harmful emissions into harmless water vapor
and carbon dioxide.
The Engine Control Module (ECM) has the ability to moni-
tor this process by using a Rear Heated Oxygen Sensor
(HO2S2). The HO2S2, located in the exhaust stream past
the catalytic converter, produces an output signal which in-
dicates the storage capacity of the catalyst. This in turn in-
dicates the catalyst’s ability to convert exhaust emissions
effectively. If the catalyst is functioning properly, the
HO2S2 signal will be far less active than the signal pro-
duced by the Front Heated Oxygen Sensor (HO2S1).
If the HO2S2 pigtail wiring, connector, or terminal is dam-
aged, the entire HO2S2 assembly must be replaced. Do
not attempt to repair the wiring, connector, or terminals. In
order for the sensor to function properly, it must have a
clean air reference provided to it. This clean air reference
is obtained by way of the HO2S2 wire(s). Any attempt to
repair the wires, connector, or terminals could result in the
obstruction of the air reference and degrade the HO2S2
performance.Conditions for Setting the DTC
S HO2S2 voltage is less than 0.05 volt in Closed
Loop control or less than 0.35 volt in Power Enrich-
ment (PE) mode.
S Engine Coolant Temperature (ECT) is greater than
60°C (140°F).
S System voltage is greater than 10 volts.
S Closed Loop test: 3 seconds delay after in Closed
Loop and air flow is greater than 9 g/sec.
S Power Enrichment test: Air/Fuel ration is less than
or equal to 13.5 and 3 seconds delay after in Power
Enrichment mode.
S DTCs P0106, P0107, P0108, P0117, P0118,
P0122, P0123, P0171, P0172, P0201, P0202,
P0203, P0204, P0300, P0336, P0337, P0351,
P0352, P0141, P0402, P0404, P0405, P0406,
P0506, P0507, P1404, and P0443 are not set.
Action Taken When the DTC Sets
S The Malfunction Indicator Lamp (MIL) will illuminate
after three consecutive ignition cycle with a fail.

ENGINE CONTROLS 1F – 389
DAEWOO V–121 BL4
S The ECM will record operating conditions at the
time the diagnostic fails. This information will be
stored in the Freeze Frame and Failure Records
buffers.
S A history DTC is stored.
Conditions for Clearing the MIL/DTC
S The MIL will turn off after four consecutive ignition
cycles in which the diagnostic runs without a fault.
S A history DTC will clear after 40 consecutive warm–
up cycles without a fault.
S The DTC(s) can be cleared by using the scan tool.
S Disconnecting the ECM battery feed for more than
10 seconds.
Diagnostic Aids
An intermittent may be caused by rubbed–through wire in-
sulation or a wire contacting the exhaust.
Check for the following conditions:
S Exhaust system – Inspect the exhaust system for
leaks. Check the exhaust between the three–way
catalytic converter and the flange for leaks, corro-
sion, or for loose or missing hardware and repair as
necessary.
S Poor connection or damaged harness – Ensure that
the HO2S2 pigtail is not contacting the exhaust.
Check for the following conditions:
S Improper mating
S Broken locks
S Improperly formedS Damaged terminals
S Poor terminal–to–wire connection
S Damaged harness
S Intermittent test – Observe the HO2S2 on the scan
tool while moving related connections and the wir-
ing harness with the ignition ON. If the failure is in-
duced, the HO2S2 display will change. This may
help isolate the location of the malfunction.
Test Description
Number(s) below refer to the step number(s) on the Diag-
nostic Table.
1. The On–Board Diagnostic (EOBD) System Check
prompts the technician to complete some basic
checks and store the freeze frame and failure re-
cords data on the scan tool if applicable. This
creates an electronic copy of the data taken when
the malfunction occurred. The information is then
stored on the scan tool for later reference.
2. This step determines if DTC P0137 is the result of
a hard failure or an intermittent condition.
4. Jumping the HO2S2 low circuit, terminal 4 to
ground is necessary to allow the ECM to display
the supplied bias voltage. If the voltage is between
0.35 and 0.55 volt, then the wiring and ECM are
OK.
6. The replacement ECM must be reprogrammed.
Refer to the latest Techline procedure for ECM re-
programming.
DTC P0137 – Rear Heated Oxygen Sensor (HO2S2) Low Voltage
StepActionValue(s)YesNo
1Perform an On–Board Diagnostic (EOBD) System
Check.
Was the check performed?–Go to Step 2Go to
”On–Board
Diagnostic Sys-
tem Check”
21. Install a scan tool to the Data Link Connector
(DLC).
2. Turn the ignition ON.
Is the Rear Heated Oxygen Sensor (HO2S2) volt-
age less than the value specified?0.1 VGo to Step 4Go to Step 3
31. Start the engine.
2. Review the Freeze Frame data and note the
parameters.
3. Operate the vehicle within the Freeze frame
conditions and Conditions For Setting the DTC
as noted.
Is the HO2S2 voltage less than the specified value?0.4 VGo to Step 4Go to Step 8
41. Turn the ignition OFF.
2. Disconnect HO2S2 connector.
3. Connect a jumper wire between terminal 1 of
HO2S2 connector and ground.
4. Turn the ignition ON.
Does the scan tool indicate that the HO2S2 voltage
is within the specified value?350–550 mVGo to Step 7Go to Step 5