2004 DAEWOO LACETTI Vacuum valve

1F – 158IENGINE CONTROLS
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P0171
FUEL TRIM SYSTEM TOO LEAN
System Description
If the adaptation value threshold is permanently exceed-
ed, the deviation of the adaptive terms enables to detect
a slow default coming out. Two time counters (one for the
rich side and another one for the lean side) are increased
while the lambda controller exceeds the adaptation
thresholds. As soon as one of the time counters reaches
its maximum value, the error is detected.
The aim of this test is to simulate a failure that would result
in exceeding the adaptive terms. Two kinds of failure must
be created.
S A lean side deviation: P0171
S A rich side deviation : P0172
It is thus necessary to determine, for each kind of failure,
the limit good and the limit bad. For a given failure, mea-
sure the emission threshold until the legal emission
thresholds are exceeded.
Note that the problem is due to the emission thresholds re-
quired, it is not simple to disturb the system so that the
emission thresholds will be exceeded. The tuning has
been made thanks to a dedicated calibration but, as such
a procedure is not permitted by the regulation, it is neces-
sary to create some material malfunction (fuel pressure
regulator, fuel injector, air leakage...).
Conditions for Setting the DTC
S DTCs P0107, P0108, P0112, P0113, P0117,
P0118, P0122, P0123, P0131, P0132, P0337,
P0338, P0341, P0342, P0400, P1319, P1402,
P1404, P1405, P1671 and P1672 are not set.
S Coolant temperature is greater than 20°C (68°F).
(1.4L DOHC)
S Coolant temperature is greater than 80°C (176°F).
(1.6L DOHC)
S Manifold Absolute Pressure (MAP) is greater than
70 kPa (10.2 psi).
S System is in closed loop.
Action Taken When the DTC Sets
S The Malfunction Indicator Lamp (MIL) will illuminate
after three consecutive trip with a fail.
S The ECM will record operating conditions at the
time the diagnostic fail. 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 DTC(s) can be cleared by using the scan tool.
S Disconnecting the ECM battery feed for 10 sec-
onds.
Diagnostic Aids
Important : After repairs, use the scan tool Fuel Trim Re-
set function to reset the long–term fuel trim to 128 (0%).
S Fuel pressure – The system will be lean if the pres-
sure is too low. It may be necessary to monitor fuel
pressure while driving the vehicle at various road
speeds and/or loads to confirm.
S 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. Discon-
necting the MAP sensor will allow the ECM to sub-
stitute a fixed (default) value for the MAP sensor. If
the lean condition is gone when the sensor is dis-
connected, 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 P0171.
Check for poor O2S or MAP sensor connection at the
ECM. Inspect the harness connectors for the following
conditions:
S Backed–out terminals
S Improper mating
S Broken locks
S Improperly formed
S Damaged terminals
S Poor terminal–to–wire connection
Inspect the wiring harness for damage. If the harness ap-
pears to be OK, observe the O2S display on the scan tool
while moving the connectors and the wiring harness re-
lated to the engine harness. A change in the display will
indicate the location of the fault.
Check the brake power booster check valve for possible
leaks.

1F – 160IENGINE CONTROLS
DAEWOO V–121 BL4
StepNo Yes Value(s) Action
8Lean condition is not present.
Does a driveability problem exist?–Go to
”Symptom
Diagnosis”Go to Step 16
91. Visually/physically inspect the following items
for vacuum leaks:
S Intake manifold.
S Throttle body.
S Injector O–rings.
2. Repair any leaks found as necessary.
Is the repair complete?–Go to Step 16Go to Step 16
10Allow the engine to idle.
Are the Idle Air Control (IAC) counts above the spe-
cified value?5Go to Step 11Go to Step 12
11Check the fuel for excessive water, alcohol, or other
contaminants and correct the contaminated fuel
condition if present.
Is the repair complete?–Go to Step 16Go to Step 13
12Check the IAC valve performance. Refer to ”DTC
P0506 Idle Speed RPM Lower Than Desired Idle
Speed” or ”DTC P0507 Idle Speed RPM Higher
Than Desired Idle Speed” in this section and repair
as necessary.
Is the repair complete?–Go to Step 16Go to Step 13
131. Connect a fuel pressure gauge to the fuel sys-
tem.
2. Turn the ignition OFF for at least 10 seconds.
3. Turn the ignition ON, with the engine OFF. The
fuel pump will run for approximately 2–3 sec-
onds. It may be necessary to cycle the ignition
switch ON more than once to obtain maximum
fuel pressure.
4. Note the fuel pressure with the fuel pump run-
ning. The pressure should be within the speci-
fied value. When the fuel pump stops, the pres-
sure may vary slightly then hold steady.
Is the fuel pressure steady and does the fuel pres-
sure hold?241–276 kPa
(35–40 psi)Go to Step 14Go to
”Fuel System
Diagnosis”
141. Start and idle the engine at normal operating
temperature.
2. The fuel pressure noted in the above step
should drop by the indicated value.
Does the fuel pressure drop by the indicated value?21–69 kPa
(3–10 psi)Go to
”Fuel Injector
Balance Test”Go to
”Fuel System
Diagnosis”
15Replace the MAP sensor.
Is the action complete?–Go to Step 16–

1F – 218IENGINE CONTROLS
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P0400
EXHAUST GAS RECIRCULATION OUT OF LIMIT
Circuit Description
An Exhaust Gas Re–circulation (EGR) system is used to
lower oxides of nitrogen (NOx) emission levels caused by
high combustion temperatures. It accomplishes this by
feeding small amounts of exhaust gases back into the
combustion chamber. When the air/fuel mixture is diluted
with the exhaust gases, combustion temperatures are re-
duced.
A linear EGR valve is used on this system. The linear EGR
valve is designed to accurately supply exhaust gases to
the engine without the use of intake manifold vacuum. The
valve controls exhaust flow going into the intake manifold
from the exhaust manifold through an orifice with a engine
control module(ECM) controlled pintle. The ECM controls
the pintle position using inputs from the Throttle Position
(TP) and the Manifold Absolute Pressure (MAP) sensor.
The ECM then commands the EGR valve to operate when
necessary by controlling an ignition signal through the
ECM. This can be monitored on a scan tool as the Desired
EGR position.
The ECM monitors the results of its command through a
feedback signal. By sending a 5 volt reference and a
ground to the EGR valve, a voltage signal representing the
EGR valve pintle position is sent to the ECM. This feed-back signal can also be monitored on a scan tool and is the
actual position of the EGR pintle. The actual EGR position
should always be near the commanded or Desired EGR
position.
This Diagnostic Trouble Code(DTC) will detect an open or
short circuit.
Conditions for Setting the DTC
S The vehicle is part load.
S The engine controls system is in closed loop.
S Engine Coolant Temperature (ECT) is higher than
70°C (158°F). (1.4L DOHC)
S Engine Coolant Temperature (ECT) is higher than
60°C (140°F). (1.6L DOHC)
S Mass Air Flow is between 120~230mg/tdc.
(1.4L DOHC)
S Mass Air Flow is between 71~174mg/tdc.
(1.6L DOHC)
S Engine Speed is Between 1,800~2,400rpm.
(1.4L DOHC)
S Engine Speed is Between 1,950~2,600rpm.
(1.6L DOHC)
S Intake Air Temperature(IAT) is higher than
15°C(59°F).
S Manifold Absolute Pressure is greater than 75kPA.
S The EGR is higher than 10%.

ENGINE CONTROLS 1F – 221
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P0404
EXHAUST GAS RECIRCULATION OPENED
Circuit Description
An Exhaust Gas Re–circulation (EGR) system is used to
lower oxides of nitrogen (NOx) emission levels caused by
high combustion temperatures. It accomplishes this by
feeding small amounts of exhaust gases back into the
combustion chamber. When the air/fuel mixture is diluted
with the exhaust gases, combustion temperatures are re-
duced.
A linear EGR valve is used on this system. The linear EGR
valve is designed to accurately supply exhaust gases to
the engine without the use of intake manifold vacuum. The
valve controls exhaust flow going into the intake manifold
from the exhaust manifold through an orifice with a engine
control module(ECM) controlled pintle. The ECM controls
the pintle position using inputs from the Throttle Position
(TP) and the Manifold Absolute Pressure (MAP) sensor.
The ECM then commands the EGR valve to operate when
necessary by controlling an ignition signal through the
ECM. This can be monitored on a scan tool as the Desired
EGR position.
The ECM monitors the results of its command through a
feedback signal. By sending a 5 volt reference and a
ground to the EGR valve, a voltage signal representing the
EGR valve pintle position is sent to the ECM. This feed-back signal can also be monitored on a scan tool and is the
actual position of the EGR pintle. The actual EGR position
should always be near the commanded or Desired EGR
position.
This Diagnostic Trouble Code(DTC) will detect an open or
short circuit.
Conditions for Setting the DTC
S EGR circuit is a short to ground or an open condi-
tion exist.
Action Taken When the DTC Sets
S The Malfunction Indicator Lamp (MIL) will illuminate
after three consecutive trip with a fail.
S The ECM will record operating conditions at the
time the diagnostic fail. 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 DTC(s) can be cleared by using the scan tool.

1F – 224IENGINE CONTROLS
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P0405
EGR PINTLE POSITION SENSOR LOW VOLTAGE
Circuit Description
An Exhaust Gas Re–circulation (EGR) system is used to
lower oxides of nitrogen (NOx) emission levels caused by
high combustion temperatures. It accomplishes this by
feeding small amounts of exhaust gases back into the
combustion chamber. When the air/fuel mixture is diluted
with the exhaust gases, combustion temperatures are re-
duced.
A linear EGR valve is used on this system. The linear EGR
valve is designed to accurately supply exhaust gases to
the engine without the use of intake manifold vacuum. The
valve controls exhaust flow going into the intake manifold
from the exhaust manifold through an orifice with a engine
control module(ECM) controlled pintle. The ECM controls
the pintle position using inputs from the Throttle Position
(TP) and the Manifold Absolute Pressure (MAP) sensor.
The ECM then commands the EGR valve to operate when
necessary by controlling an ignition signal through the
ECM. This can be monitored on a scan tool as the Desired
EGR position.
The ECM monitors the results of its command through a
feedback signal. By sending a 5 volt reference and a
ground to the EGR valve, a voltage signal representing the
EGR valve pintle position is sent to the ECM. This feed-back signal can also be monitored on a scan tool and is the
actual position of the EGR pintle. The actual EGR position
should always be near the commanded or Desired EGR
position.
This Diagnostic Trouble Code(DTC) will detect an open or
short circuit.
Conditions for Setting the DTC
S EGR voltage is less than 0.01V.
Action Taken When the DTC Sets
S The Malfunction Indicator Lamp (MIL) will illuminate
after three consecutive trip with a fail.
S The ECM will record operating conditions at the
time the diagnostic fail. 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 DTC(s) can be cleared by using the scan tool.
S Disconnecting the ECM battery feed for more than
10 seconds.

ENGINE CONTROLS 1F – 227
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P0406
EGR PINTLE POSITION SENSOR HIGH VOLTAGE
Circuit Description
An Exhaust Gas Re–circulation (EGR) system is used to
lower oxides of nitrogen (NOx) emission levels caused by
high combustion temperatures. It accomplishes this by
feeding small amounts of exhaust gases back into the
combustion chamber. When the air/fuel mixture is diluted
with the exhaust gases, combustion temperatures are re-
duced.
A linear EGR valve is used on this system. The linear EGR
valve is designed to accurately supply exhaust gases to
the engine without the use of intake manifold vacuum. The
valve controls exhaust flow going into the intake manifold
from the exhaust manifold through an orifice with a engine
control module(ECM) controlled pintle. The ECM controls
the pintle position using inputs from the Throttle Position
(TP) and the Manifold Absolute Pressure (MAP) sensor.
The ECM then commands the EGR valve to operate when
necessary by controlling an ignition signal through the
ECM. This can be monitored on a scan tool as the Desired
EGR position.
The ECM monitors the results of its command through a
feedback signal. By sending a 5 volt reference and a
ground to the EGR valve, a voltage signal representing the
EGR valve pintle position is sent to the ECM. This feed-back signal can also be monitored on a scan tool and is the
actual position of the EGR pintle. The actual EGR position
should always be near the commanded or Desired EGR
position.
This Diagnostic Trouble Code(DTC) will detect an open or
short circuit.
Conditions for Setting the DTC
S EGR voltage is higher than 4.99V.
Action Taken When the DTC Sets
S The Malfunction Indicator Lamp (MIL) will illuminate
after three consecutive trip with a fail.
S The ECM will record operating conditions at the
time the diagnostic fail. 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 DTC(s) can be cleared by using the scan tool.
S Disconnecting the ECM battery feed for more than
10 seconds.

1F – 232IENGINE CONTROLS
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P0444
EVAP PURGE CONTROL CIRCUIT NO SIGNAL
Circuit Description
The evaporative emission (EVAP) system includes the fol-
lowing components :
S Fuel tank.
S EVAP vent solenoid.
S Fuel tank pressure sensor.
S Fuel pipes and hoses.
S Fuel vapor lines.
S Fuel cap.
S EVAP canister.
S Purge lines.
S EVAP canister purge valve.
S EVAP service port.
The evaporative emission system is checked by applying
vacuum to the EVAP system and monitoring for a vacuum
decay. The engine control module(ECM) monitors the
vacuum level through the fuel tank pressure sensor signal.
At the appropriate time, the EVAP canister purge valve
and the EVAP vent solenoid are turned on, allowing the en-
gine to draw a small vacuum on the entire EVAP system.
After the desired vacuum level has been achieved, the
EVAP canister purge valve is turned OFF, sealing the sys-tem. If a sufficient vacuum level cannot be achieved, a
large leak is indicated. This can be caused by the following
conditions :
Missing or faulty fuel cap.
Disconnected or faulty fuel tank pressure sensor.
Disconnected, damaged, pinched, or blocked EVAP
purge line.
Disconnected or faulty EVAP canister purge valve.
Disconnected or faulty EVAP vent solenoid.
Open ignition feed circuit to the EVAP vent or purge sole-
noid.
Damaged EVAP canister.
Leaking fuel sensor assembly O–ring.
Leaking fuel tank or fuel filler beck.
Any of the above conditions can set DTC P0444.
The test is failed if the tank vacuum is less than 10 in H20
for 15 seconds and the manifold vacuum integral is greater
than 49512 (proportional to purge mass from the tank).
Conditions for Setting the DTC
S The canister purge solenoid circuit is an open con-
dition exist.

ENGINE CONTROLS 1F – 233
DAEWOO V–121 BL4
Action Taken When the DTC Sets
S The Malfunction Indicator Lamp (MIL) will illuminate
after three consecutive trip with a fail.
S The ECM will record operating conditions at the
time the diagnostic fail. 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 DTC(s) can be cleared by using the scan tool.
S Disconnecting the ECM battery feed for more than
10 seconds.
Diagnostic Aids
Although this DTC is considered a type. A diagnostic, it
acts like a type B diagnostic under certain conditions.
Whenever this diagnostic reports the system has passed,
or if the battery is disconnected, the diagnostic must fail
twice before setting a DTC. The initial failure is not re-ported to the diagnostic executive or displayed on a scan
tool. A passing system always reports to the diagnostic
executive immediately.
Check for the following conditions :
S Missing or damaged fuel cap.
S Missing or damaged O–rings at fuel vapor and
EVAP purge line canister fittings.
S Cracked or punctured EVAP canister.
S Damaged source vacuum line, EVAP purge line,
EVAP vent hose or fuel tank vapor line.
S Poor connection at the ECM. Inspect the harness
connectors for the following conditions.
S Backed–out terminals.
S Improper mating.
S Broken locks.
S Improperly formed.
S Damaged terminals.
S Poor terminal–to–wire connection.
S Damaged harness. Inspect the wiring harness to
the EVAP vent solenoid, EVAP canister purge
valve, and the fuel tank pressure sensor for an in-
termittent open or short circuit.
S Kinked, pinched or plugged vacuum source, EVAP
purge, or fuel tank vapor line. Verify that the lines
are not restricted.
DTC P0444 – EVAP Purge Control Circuit No Signal
StepActionValue(s)YesNo
1Perform an Euro On–Board Diagnostic (EOBD)
System Check.
Is the system check complete?–Go to Step 2Go to
”On–Board
Diagnostic Sys-
tem Check”
21. Disconnect the evaporative emission (EVAP)
canister purge valve connector.
2. Connect a test light between the EVAP canister
purge valve connector terminal 1 and battery
positive.
Is the test light ON?–Go to Step 3Go to Step 5
31. Disconnect the ECM connector.
2. Connect a test light between the ECM connec-
tor terminal 65 and ground.
Is the test light ON?–Go to Step 4Go to Step 6
41. Repair the line break in the wire between the
EVAP canister purge valve connector 2 and the
ECM connector terminal 65.
2. Clear any Diagnostic Trouble Codes (DTCs)
from the ECM.
3. Perform the diagnostic system check.
Is the repair complete?–System OK–