2004 DAEWOO LACETTI Ground

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 voltage with-
in the specified value?407–509 mVGo to
”Diagnostic
Aids”Go to Step 5
5Check the HO2S1 signal circuit, terminal 4 for a
short to ground and repair as needed.
Is the repair necessary.–Go to Step 7Go to Step 6
6S Turn the ignition OFF.
S Replace the Engine Control Module (ECM).
Is the repair complete?–Go to Step 7–
71. If disconnected, reconnect HO2S1 connector.
2. Using the scan tool, clear the Diagnostic
Trouble Codes (DTCs).
3. Start the engine and idle at normal operating
temperature.
4. Operate the vehicle within the Conditions for
setting this DTC as specified in the supporting
text.
Does the scan tool indicate that this diagnostic has
run and passed?–Go to Step 8Go to Step 2
8Check if any additional DTCs are set.
Are any DTCs displayed that have not been diag-
nosed?–Go to applica-
ble DTC tableSystem OK

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 (ECM) side
HO2S1 signal circuit to ground.
Does the scan tool indicate the HO2S1 voltage be-
low the specified value?500 mVGo to
”Diagnostic
Aids”Go to Step 5
5Check the HO2S1 signal circuit, terminal 4 for a
short to voltage and repair as needed.
Is the repair complete?–Go to Step 7Go to Step 6
6S Turn the ignition OFF.
S Replace the ECM.
Is the repair complete?–Go to Step 7–
71. If disconnected, reconnect HO2S1 connector.
2. Using the scan tool, clear the Diagnostic
Trouble Codes (DTCs).
3. Start the engine and idle at normal operating
temperature.
4. Operate the vehicle within the Conditions for
setting this DTC as specified in the supporting
text.
Does the scan tool indicate that this diagnostic has
run and passed?–Go to Step 8Go to Step 2
8Check if any additional DTCs are set.
Are any DTCs displayed that have not been diag-
nosed?–Go to applica-
ble DTC tableSystem OK

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–

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

1F – 384IENGINE CONTROLS
DAEWOO V–121 BL4
StepNo Yes Value(s) Action
61. Idle the engine.
2. Remove the jumper wire.
3. Using a voltmeter, measure the voltage be-
tween terminal 4 of HO2S1 and ground
Is the voltage above the specified value?600 mVGo to Step 7Go to Step 11
71. Turn the engine OFF.
2. Using a voltmeter, measure the voltage be-
tween terminal 4 of the HO2S1 and ground.
Is the voltage below the specified value?300 mVGo to Step 9Go to Step 11
8Check the HO2S1 low circuit for an open or short to
ground between terminal 3 of the HO2S1 and termi-
nal M29 of the ECM and repair as needed.
Is the repair complete?–Go to Step 12Go to Step 10
9Check the HO2S1 signal circuit for an open or short
to ground between terminal 4 of the HO2S1 and ter-
minal M12 of the ECM and repair as needed.
Is the repair complete?–Go to Step 12Go to Step 10
10S Turn the ignition OFF.
S Replace the ECM.
Is the repair complete?–Go to Step 12–
11Replace the HO2S1.
Is the repair complete?–Go to Step 12–
121. Using the scan tool, clear the Diagnostic
Trouble Codes (DTCs).
2. Start the engine and idle at normal operating
temperature.
3. Operate the vehicle within the Conditions for
setting this DTC as specified in the supporting
text.
Does the scan tool indicate that this diagnostic has
run and passed?–Go to Step 13Go to Step 2
13Check if any additional DTCs are set.
Are any DTCs displayed that have not been diag-
nosed?–Go to
”Applicable
DTC table”System OK

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–

ENGINE CONTROLS 1F – 387
DAEWOO V–121 BL4
StepNo Yes Value(s) Action
9Check the connections terminal 4 at the HO2S1 con-
nector and repair as necessary.
Is the repair complete?–Go to Step 13Go to Step 12
10Replace the HO2S1 sensor.
Is the action complete?–Go to Step 13–
11Repair the open in the ground circuit.
Is the action complete?–Go to Step 13–
12Repair the open in the ignition feed circuit.
Is the action complete?–Go to Step 13–
131. Using the scan tool, clear the Diagnostic
Trouble Codes (DTCs).
2. Start the engine and idle at normal operating
temperature.
3. Operate the vehicle within the conditions for
setting this DTC as specified in the supporting
text.
Does the scan tool indicate that this diagnostic has
run and passed?–Go to Step 14Go to Step 2
14Check if any additional DTCs are set.
Are any DTCs displayed that have not been diag-
nosed?–Go to
”Applicable
DTC table”System OK