2004 DAEWOO LACETTI check engine light

ENGINE CONTROLS 1F – 471
DAEWOO V–121 BL4
The EGR Decel Filter value should always be at –3 or low-
er. If the EGR Decel Filter number becomes more positive
(towards 0 or more), then the EGR system is becoming re-
stricted. Look for possible damage to the EGR pipe or for
a restriction caused by carbon deposits in the EGR pas-
sages or on the EGR valve.
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. Commanding the EGR valve open determines
whether the EGR system can control the EGR
valve accurately and if the fault is present. The dif-
ference between the current and commanded posi-
tion is greater than 15%.
3. When the EGR valve electrical connector is discon-
nected, the scan tool should display the Actual
EGR Position as 0%. If it does not, the fault lies
either in the EGR signal circuit or the ECM.
4. There may be a slight delay for the voltage dis-
played on the DVM to change after the scan tool
commands the EGR valve to operate.
5. An open or poor connection condition may have
caused this DTC to set. Be sure to check the termi-
nals for being backed out, improperly formed or
damaged, and for poor tension.
7. The test light will have glowed brightly in the pre-
vious step if the EGR control circuit was shorted to
B+ and the Actual EGR Position on the scan toolwill display 100%. A test light that did not illuminate,
indicates that the circuit may be open or shorted to
ground.
9. If the EGR valve 5 volt reference is shorted to volt-
age, the digital voltmeter (DVM) will read battery
voltage and additional DTCs may be set and the
engine performance will be poor.
12. The replacement ECM must be reprogrammed.
Refer to the latest Techline procedure for ECM re-
programming.
13. Although the circuitry acted correctly when
checked, a problem may still lie within the terminals
which would not show up in probe type testing. Be
sure to check the terminals for being backed out,
improperly formed or damaged, and for poor ten-
sion.
17. All circuits to the EGR valve are OK at this point.
The fault lies internally in the EGR valve and, there-
fore, must be replaced. Be sure all gasket material
is removed from the EGR mounting surface. Even
a small amount of material may cause a DTC
P0401 to set.
18. Check the terminals for being backed out, improp-
erly formed or damaged, and for poor tension.
19. Clearing DTCs is a very important step for this
diagnostic. The clearing function allows the EGR
valve to relearn a new pintle position as the old
pintle position was inaccurate due to the failure that
caused the DTC. The DTC must be cleared with
the ignition ON, engine OFF or when the engine is
idling. If the ECM sees a EGR command, the new
pintle will not be learned.
20. 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 P0402 – Exhaust Gas Recirculation Excessive Flow
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.
3. Command the Exhaust Gas Recirculation
(EGR) valve to the specific values.
Does the Actual EGR Position follow the Desired
EGR Position?25%, 50%,
75%, 100%Go to Step 19Go to Step 3
31. Turn the ignition OFF.
2. Disconnect the EGR valve.
3. Turn the ignition ON.
4. With a test light connected to B+, probe the
EGR valve wiring harness connector terminal
2.
Does the test light illuminate?–Go to Step 4Go to Step 5

1F – 472IENGINE CONTROLS
DAEWOO V–121 BL4
StepNo Yes Value(s) Action
41. Using a voltmeter, measure the voltage at the
EGR valve wiring harness connector terminal
1.
2. Command the EGR valve open with the scan
tool.
After command is raised, is the voltage displayed on
the voltmeter vary between specified value?0 to
5 VGo to Step 6Go to Step 7
5Repair the open or poor connection in the EGR
ground circuit as needed.
Is the repair complete?–Go to Step 19
6With a test light connected to ground, probe the EGR
valve wiring harness connector terminal 3.
Does the test light illuminate?–Go to Step 8Go to Step 9
7With a test light connected to ground, probe the EGR
valve wiring harness connector terminal 1, without
commanding the EGR valve with scan tool.
Dose the test light illuminate?–Go to Step 10Go to Step 11
8Check the signal circuit for a short to voltage and re-
pair as needed.
Is the repair complete?–Go to Step 19Go to Step 12
9With a voltmeter connected to the ground, probe the
5 volt reference circuit at terminal 4 of the EGR valve
wiring harness connector.
Is the voltage near the specified value?5 vGo to Step 13Go to Step 14
10Check the control circuit for a short to voltage and re-
pair as needed.
Is a repair necessary.–Go to Step 19Go to Step 12
11With a test light connected to B+ and again probe the
control circuit at terminal 1.
Dose the test light illuminate?–Go to Step 15Go to Step 16
121. Turn the ignition OFF.
2. Replace the Engine Control Module (ECM).
Is the repair complete?–Go to Step 19–
13Check the EGR ground circuit for poor connection or
proper terminal tension at the ECM and repair as
needed.
Is a repair necessary?–Go to Step 19Go to Step 17
14Check the 5 volt reference circuit for a short to volt-
age and repair as needed.
Is the repair necessary?–Go to Step 19Go to Step 12
15Check the control circuit 1 for short to ground and re-
pair as needed.
Is the repair necessary?–Go to Step 19Go to Step 12
16Check the control circuit at terminal 1 for an open or
poor connection at EGR valve connector and repair
as needed.
Is a repair necessary?–Go to Step 19Go to Step 18
171. Turn the ignition OFF.
2. Replace the EGR valve.
Is the repair complete?–Go to Step 19–

ENGINE CONTROLS 1F – 475
DAEWOO V–121 BL4
the Actual EGR and Desired EGR Positions on a cold ve-
hicle with a scan tool, the fault can be easily verified.
Check the freeze frame data to determine if the DTC set
when the vehicle was cold by viewing the Engine Coolant
Temperature (ECT).
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. Commanding the EGR valve open determines
whether the EGR system can control the EGR
valve accurately and if the fault is present. The dif-
ference between the current and commanded posi-
tion is greater than 15%.
3. When the EGR valve electrical connector is discon-
nected, the scan tool should display the Actual
EGR Position as 0%. If it does not, the fault lies
either in the EGR signal circuit or the ECM.
4. There may be a slight delay for the voltage dis-
played on the DVM to change after the scan tool
commands the EGR valve to operate.
5. An open or poor connection condition may have
caused this DTC to set. Be sure to check the termi-
nals for being backed out, improperly formed or
damaged, and for poor tension.
7. The test light will have glowed brightly in the pre-
vious step if the EGR control circuit was shorted to
B+ and the Actual EGR Position on the scan toolwill display 100%. A test light that did not illuminate,
indicates that the circuit may be open or shorted to
ground.
9. If the EGR valve 5 volt reference is shorted to volt-
age, the digital voltmeter (DVM) will read battery
voltage and additional DTCs may be set and the
engine performance will be poor.
12. The replacement ECM must be reprogrammed.
Refer to the latest Techline procedure for ECM re-
programming.
13. Although the circuitry acted correctly when
checked, a problem may still lie within the terminals
which would not show up in probe type testing. Be
sure to check the terminals for being backed out,
improperly formed or damaged, and for poor ten-
sion.
17. All circuits to the EGR valve are OK at this point.
The fault lies internally in the EGR valve and, there-
fore, must be replaced. Be sure all gasket material
is removed from the EGR mounting surface. Even
a small amount of material may cause a DTC
P0401 to set.
18. Check the terminals for being backed out, improp-
erly formed or damaged, and for poor tension.
19. Clearing DTCs is a very important step for this
diagnostic. The clearing function allows the EGR
valve to relearn a new pintle position as the old
pintle position was inaccurate due to the failure that
caused the DTC. The DTC must be cleared with
the ignition ON, engine OFF or when the engine is
idling. If the ECM sees a EGR command, the new
pintle will not be learned.
20. 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 P0404 – Exhaust Gas Recirculation Open Valve Position Error
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.
3. Command the Exhaust Gas Recirculation
(EGR) valve to the specific values.
Does the Actual EGR Position follow the Desired
EGR Position?25%, 50%,
75%, 100%Go to Step 19Go to Step 3
31. Turn the ignition OFF.
2. Disconnect the EGR valve.
3. Turn the ignition ON.
4. With a test light connected to B+, probe the
EGR valve wiring harness connector terminal
2.
Does the test light illuminate?–Go to Step 4Go to Step 5

1F – 476IENGINE CONTROLS
DAEWOO V–121 BL4
StepNo Yes Value(s) Action
41. Using a voltmeter, measure the voltage at the
EGR valve wiring harness connector terminal
1.
2. Command the EGR valve open with the scan
tool.
After command is raised, is the voltage displayed on
the voltmeter vary between specified value?0 to
5 VGo to Step 6Go to Step 7
5Repair the open or poor connection in the EGR
ground circuit as needed.
Is the repair complete?–Go to Step 19–
6With a test light connected to ground, probe the EGR
valve wiring harness connector terminal 3.
Dose the test light illuminate?–Go to Step 8Go to Step 9
7With a test light connected to ground, probe the EGR
valve wiring harness connector terminal 1, without
commanding the EGR valve with scan tool.
Dose the test light illuminate?–Go to Step 10Go to Step 11
8Check the signal circuit for a short to voltage and re-
pair as needed.
Is a repair necessary?–Go to Step 19Go to Step 12
9With a voltmeter connected to the ground, probe the
5 volt reference circuit at terminal 4 of the EGR valve
wiring harness connector.
Is the voltage near the specified value?5 vGo to Step 13Go to Step 14
10Check the control circuit for a short to voltage and re-
pair as needed.
Is a repair complete?–Go to Step 19Go to Step 12
11With a test light connected to B+ and again probe the
control circuit at terminal 1.
Dose the test light illuminate?–Go to Step 15Go to Step 16
121. Turn the ignition OFF.
2. Replace the Engine Control Module (ECM).
Is the repair complete?–Go to Step 19–
13Check the EGR ground circuit for poor connection or
proper terminal tension at the ECM and repair as
needed.
Is the repair complete?–Go to Step 19Go to Step 17
14Check the 5 volt reference circuit for a short to volt-
age and repair as needed.
Is the repair complete?–Go to Step 19Go to Step 12
15Check the control circuit at terminal 1 for short to
ground and repair as needed.
Is the repair complete?–Go to Step 19Go to Step 12
16Check the control circuit at terminal 1 for an open or
poor connection at EGR valve connector and repair
as needed.
Is the repair complete?–Go to Step 19Go to Step 18
171. Turn the ignition OFF.
2. Replace the EGR valve.
Is the repair complete?–Go to Step 19–

1F – 480IENGINE CONTROLS
DAEWOO V–121 BL4
StepNo Yes Value(s) Action
5With a test light connected to B+, probe the 5 volt ref-
erence circuit at the EGR valve wiring harness con-
nector terminal 4.
Dose the test light illuminate?–Go to Step 8Go to Step 9
6Check the 5 volt reference and signal circuit for a
poor connection or proper terminal tension and re-
pair as needed.
Is the repair complete?–Go to Step 15Go to Step 10
7With a test light connected to B+, probe the signal
circuit at terminal 3 of the EGR valve wiring harness
connector.
Dose the test light illuminate?–Go to Step 11Go to Step 12
8Check for a short to ground in EGR valve 5 volt refer-
ence circuit and repair as needed.
Is the repair complete?–Go to Step 15Go to Step 13
9Check for an open in EGR valve 5 volt reference cir-
cuit and repair as needed.
Is the repair complete?–Go to Step 15Go to Step 14
101. Turn the ignition OFF.
2. Replace the EGR valve.
Is the repair complete?–Go to Step 15–
11Check for a short to ground in the EGR valve signal
circuit and repair as needed.
Is the repair complete?–Go to Step 15Go to Step 13
12Check for an open in the EGR valve signal circuit
and repair as needed.
Is the repair complete?–Go to Step 15Go to Step 14
131. Turn the ignition OFF.
2. Replace the Engine Control Module (ECM).
Is the repair complete?–Go to Step 15–
14Check the ECM connector for a poor connection and
repair as needed.
Is the repair complete?–Go to Step 15Go to Step 13
151. 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 16Go to Step 2
16Check if any additional DTCs are set.
Are any DTCs displayed that have not been diag-
nosed?–Go to
Applicable DTC
tableSystem OK

ENGINE CONTROLS 1F – 483
DAEWOO V–121 BL4
StepNo Yes Value(s) Action
5With a test light connected to B+, probe the 5 volt ref-
erence circuit at the EGR valve wiring harness con-
nector terminal 4.
Dose the test light illuminate?–Go to Step 8Go to Step 9
6Check the 5 volt reference and signal circuit for a
poor connection or proper terminal tension and re-
pair as needed.
Is the repair complete?–Go to Step 14Go to Step 10
7With a test light connected to B+, probe the signal
circuit at terminal 3 of the EGR valve wiring harness
connector.
Dose the test light illuminate?–Go to Step 11Go to Step 13
8Check for a short to ground in EGR valve 5 volt refer-
ence circuit and repair as needed.
Is the repair complete?–Go to Step 14Go to Step 12
9Check for an open in EGR valve 5 volt reference cir-
cuit and repair as needed.
Is the repair complete?–Go to Step 14Go to Step 13
101. Turn the ignition OFF.
2. Replace the EGR valve.
Is the repair complete?–Go to Step 14–
11Check for a short to ground in the EGR valve signal
circuit and repair as needed.
Is the repair complete?–Go to Step 14Go to Step 12
121. Turn the ignition OFF.
2. Replace the Engine Control Module (ECM).
Is the repair complete?–Go to Step 14–
13Check the ECM connector for a poor connection and
repair as needed.
Is the repair complete?–Go to Step 14Go to Step 12
141. 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 15Go to Step 2
15Check if any additional DTCs are set.
Are any DTCs displayed that have not been diag-
nosed?–Go to
Applicable DTC
tableSystem OK

ENGINE CONTROLS 1F – 487
DAEWOO V–121 BL4
DTC P0443 – Evaporative Emission System Purge Solenoid
Control Circuit
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.
3. Command the Evaporative Emission (EVAP)
Purge Solenoid ON and OFF.
Does the solenoid turn ON and OFF with each com-
mand.ON–99%
OFF–0%Go to Step 3Go to Step 5
31. Turn the ignition OFF.
2. Disconnect the Engine Control Module (ECM)
connector.
3. Turn the ignition ON.
4. Using a ammeter on a 10 ampere scale, mea-
sure the current between the solenoid control
circuit, terminal M4 at the ECM connect and
ground for 2 minutes.
Does the current draw measure less than the speci-
fied value?0.75 AGo to
”Diagnostic
Aids”Go to Step 4
41. Disconnect the solenoid.
2. Using ohmmeter measure the resistance be-
tween the solenoid control circuit, terminal M4
of the ECM connector and ground.
Does the ohmmeter display infinite resistance?–Go to Step 12Go to Step 10
51. Turn the ignition OFF.
2. Disconnect the solenoid.
3. Connect a test light between the terminal 1 and
2 of the solenoid.
4. Turn the ignition ON.
5. Using the scan tool, command the solenoid ON
and OFF.
Does the test light turn ON and OFF with each com-
mand?–Go to Step 8Go to Step 6
6With a test light connected to ground, probe the igni-
tion feed circuit, terminal 1 in the solenoid harness
connector.–Go to Step 7Go to Step 11
71. Turn the ignition OFF.
2. Reconnect the solenoid.
3. Disconnect the ECM connector.
4. Turn the ignition ON.
5. With a fused jumper wire connected to ground,
probe the solenoid control circuit terminal M4 in
the ECM connector.
Does the solenoid operate?–Go to Step 9Go to Step 10
8Check the connections at the solenoid.
Is a problem found and corrected?–Go to Step 14Go to Step 12

1F – 502IENGINE CONTROLS
DAEWOO V–121 BL4
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. A normally operating IAC system will be able to be
extended and retracted by a scan tool and change
the engine idle rpm. Valve movement is verified by
an engine rpm change.
3. If the scan tool was able to command the IAC valve
smoothly, a malfunction may still exist internally
within the IAC valve. This can be checked by
checking the IAC valves internal resistance.
5. The IAC circuits always have ground or voltage sig-
nals on them in pairs. If the test light illuminates on
more or less than 2 terminals, 1 of the circuits is
shorted to voltage or open.6. The IAC circuits always have ground or voltage sig-
nals on them in pairs. If the test light illuminates on
more or less than 2 terminals, 1 of the circuits is
shorted to ground or open
8. The IAC circuits are constantly switched between
ground and voltage so the test light should blink on
all circuits when connected to ground.
10. Any circuitry, that is suspected as causing the inter-
mittent complaint, should be thoroughly checked for
backed–out terminals, improper mating, broke
locks, improperly formed or damaged terminals,
poor terminal– to–wiring connections or physical
damage to the wiring harness.
12. A test light that remains ON constantly indicates
that the circuit is shorted to voltage.
14. The replacement ECM must be reprogrammed.
Refer to the latest Techline procedure for ECM re-
programming.
16. 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 P0506 – Idle Speed RPM Lower Than Desired Idle Speed
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. Operate the engine to idle speed.
3. Transmission in park or neutral and the parking
brake set.
4. A/C is off.
5. Using scan tool, command the Idle Air Control
(IAC) valve up and down between the specified
value.
Does the rpm change smoothly when he command-
ed by the scan tool?900–1200 rpmGo to Step 3Go to Step 5
31. Turn the ignition OFF.
2. Disconnect the IAC valve connector.
3. Measure the resistance between terminal D
and C of the IAC valve.
4. Measure the resistance between terminal B
and A of the IAC valve.
Is the resistance within the specified value?40–80 WGo to Step 4Go to Step 13
41. Measure the resistance between terminal C
and B of the IAC valve.
2. Measure the resistance between terminal D
and A of the IAC valve.
Is the resistance equal to the specified value?Go to Step 15Go to Step 13