2004 DAEWOO LACETTI Service Repair Manual

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Page 617 of 2643

DAEWOO LACETTI 2004 Service Repair Manual ENGINE CONTROLS 1F – 371
DAEWOO V–121 BL4
StepNo Yes Value(s) Action
121. Using the scan tool, clear the Diagnostic
Trouble Codes (DTCs).
2. Start the engine and idle at normal operating
temper

Page 618 of 2643

DAEWOO LACETTI 2004 Service Repair Manual 1F – 372IENGINE CONTROLS
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P0131
FRONT HEATED OXYGEN SENSOR (HO2S1) LOW
VOLTAGE
Circuit Description
The Engine Control Module (ECM) supplies a voltage

Page 619 of 2643

DAEWOO LACETTI 2004 Service Repair Manual ENGINE CONTROLS 1F – 373
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 h

ENGINE CONTROLS 1F – 373
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 Fuel pressure – The system will be lean if the fuel
pressure is too low. It may be necessary to monitor
the fuel pressure while driving the vehicle at various
road speeds and/or loads to confirm. Refer to ”Fuel
System Diagnosis” in this section.
S Manifold Absolute Pressure (MAP) sensor – An
output that causes the ECM to sense a lower than
normal manifold pressure (high vacuum) can cause
the system to go lean. Disconnecting the MAP sen-
sor will allow the ECM to substitute a fixed (default)
value for the MAP sensor. If the lean condition is
gone when the sensor is disconnected, substitute a
known good sensor and recheck.
S Fuel contamination – Water, in even small amounts
near the in–tank fuel pump inlet can be delivered to
the injector. The water causes a lean exhaust and
can set DTC P0131.
S Sensor harness – The HO2S1 sensor pigtail may
be mis–positioned and contacting the exhaust man-
ifold.
S Engine misfire – A misfiring cylinder will result in
unburned oxygen in the exhaust, which could cause
DTC P0131 to set. Refer to DTC P0300 Engine
Misfire in this section.S Cracked Front Heated Oxygen Sensor – A cracked
HO2S1 or poor ground at the sensor could cause
DTC P0131. Refer to”Symptoms Diagnosis” in this
section.
S Plugged fuel filter – A plugged fuel filter can cause
a lean condition and cause a DTC P0131 to set.
S Plugged Front Heated Oxygen Sensor – A plugged
reference port on the HO2S1 will indicate a lower–
than–normal voltage output from the HO2S1.
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 P0131 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 DTC P0134. 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” for additional checks and information.
DTC P0131 – Front Heated Oxygen Sensor (HO2S1) Low Voltage
StepActionValue(s)YesNo
1Perform an On–Board Diagnostic (EOBD) System
Check.
Is the check completed?–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?0.1 VGo 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?0.1 VGo to Step 4Go to Step 7

Page 620 of 2643

DAEWOO LACETTI 2004 Service Repair Manual 1F – 374IENGINE CONTROLS
DAEWOO V–121 BL4
StepNo Yes Value(s) Action
41. Turn the ignition OFF.
2. Disconnect HO2S1 connector.
3. Turn the ignition ON.
Does the scan tool indicate the HO2S1 vol

Page 621 of 2643

DAEWOO LACETTI 2004 Service Repair Manual ENGINE CONTROLS 1F – 375
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P0132
FRONT HEATED OXYGEN SENSOR (HO2S1) HIGH
VOLTAGE
Circuit Description
The Engine Control Module (ECM) supplies a voltag

ENGINE CONTROLS 1F – 375
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P0132
FRONT HEATED OXYGEN SENSOR (HO2S1) HIGH
VOLTAGE
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” in
this section.
Conditions for Setting the DTCS HO2S1 voltage is greater than 0.952 volts.
S Closed loop stoichiometry.
S Engine Coolant Temperature (ECT) is greater than
60°C(140°F).
S System voltage is greater than 10 volts.
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 conditions are met.
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.
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.

Page 622 of 2643

DAEWOO LACETTI 2004 Service Repair 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

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

Page 623 of 2643

DAEWOO LACETTI 2004 Service Repair Manual ENGINE CONTROLS 1F – 377
DAEWOO V–121 BL4
StepNo Yes Value(s) Action
41. Turn the ignition OFF.
2. Disconnect HO2S1 connector.
3. Turn the ignition ON.
4. Jumper the Engine Control Module (EC

Page 624 of 2643

DAEWOO LACETTI 2004 Service Repair Manual 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 moni

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.

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