2004 DAEWOO LACETTI sensor

1F – 152IENGINE CONTROLS
DAEWOO V–121 BL4
DTC P0138 – Rear Heated Oxygen Sensor High Voltage
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. Turn the ignition switch to ON, with the engine
OFF.
2. Install a scan tool.
3. Engine at operating temperature.
4. Run the engine at 1,200rpm.
Does the scan tool the Heated oxygen(O2) sensor
voltage within the value specified?More than
1.2VGo to Step 3Go to Step 6
31. Turn the ignition switch to LOCK.
2. Disconnect the Heated O2 sensor connector
and engine control module (ECM) connector.
3. Check the Heated O2 sensor wire between the
Heated O2 sensor connector terminal 4 and
ECM connector terminal 64 for an open or
short to battery voltage.
Is the problem found?–Go to Step 4Go to Step 5
41. Repair the wire of the connector terminal as
needed.
2. Clear the DTCs from the ECM.
3. Road tests the vehicle.
4. Perform the diagnostic system check.
Is the repair complete?–System OK–
51. Turn the ignition switch to LOCK.
2. Replace the Heated O2 sensor.
3. Road tests the vehicle.
4. Perform the diagnostic system check.
Is the replacement complete?–Go to Step 7–
61. Turn the ignition switch to LOCK.
2. Replace the ECM.
3. Road tests the vehicle.
4. Perform the diagnostic system check.
Is the replacement complete?–Go to Step 7–
7Check if any additional DTCs are set.
Are any DTCs displaced that have not been diag-
nosed?–Go to applica-
ble DTC tableSystem OK

ENGINE CONTROLS 1F – 153
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P0140
REAR HEATED OXYGEN SENSOR NO ACTIVITY
Circuit Description
The engine control module (ECM) supplies a voltage of
about 450mm volts between the ECM terminals 64 and 16.
The oxygen (O2) sensor varies the voltage within a range
of about 1volt if the exhaust is rich, down to about 100mm
volts if the exhaust is lean. The O2 sensor is like an open
circuit and produces no voltage when it is below
360°C(600°F). An open O2 sensor circuit or a cold O2
sensor causes ”open loop” operation.
Conditions for Setting the DTC
S The engine controls system is in closed loop.
S Engine Coolant Temperature is higher than 75°C
(167°F). (1.4L DOHC)
S Engine Coolant Temperature is higher than 70°C
(158°F). (1.6L DOHC)
S The engine speed is between 1,760 rpm and 2,368
rpm. (1.4L DOHC)
S The engine speed is between 1,300 rpm and 3,000
rpm. (1.6L DOHC)
S The vehicle speed is between 47 km/h (29.2 mph)
and 80 km/h (49.7 mph). (1.4L DOHC)
S The vehicle speed is between 26 km/h (16.2 mph)
and 54 km/h (33.6 mph). (1.6L DOHC)
S The manifold air pressure is higher than 700hPa.S No transition from rich side to lean side or lean side
to rich side during 7.8 seconds even with a forcing
of O2 sensor controller.
S DTCs P0107, P0108, P0112, P0113, P0117,
P0118, P0122, P0123, P0137, P0138, P1671,
P0300, P0335, P0336, P0341, P0400, P0404,
P0405, P0644, P0645 are NOT SET.
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 coolant fan turns ON.
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.
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.

1F – 154IENGINE CONTROLS
DAEWOO V–121 BL4
Diagnostic Aids
Normal scan tool voltage varies between 0.15 to 8.5mV
while in Closed Loop. If DTC P0140 is intermittent, refer
to ”Intermittents” in this section.
DTC P0140 – Rear Heated Oxygen Sensor No Activity
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. Run the engine to above the specified operat-
ing temperature.
2. Install a scan tool.
3. Operate the engine above the specified rpm for
2 minuets.
Does the scan tool the indicate Closed Loop?80°C(176°F)
1,200rpmGo to Step 3Go to Step 4
31. Turn the Turn the ignition switch to ON.
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?
Does the scan tool the indicate Closed Loop?–Go to Step 12Go to Step 4
4Disconnect the Heated O2 sensor connector and
jumper the Heated O2 sensor low circuit, terminal 3
to ground.
Is the HO2 voltage below the specified value and
does the scan tool indicate the heated oxygen sen-
sor heater voltage within the specified value?0.5VGo to Step 5Go to Step 6
5Check the Heated O2 sensor connector for malfunc-
tion terminals or poor connection and repair as nec-
essary.
Is repair necessary?–Go to Step 12Go to Step 9
61. Turn the ignition switch to On.
2. Remove the jumper wire.
3. Using a digital voltmeter(DVM), measure the
voltage between the Heated O2 sensor signal
circuit, terminal 4 to ground.
Does the Heated O2 sensor voltage measure above
the specified value?0.6VGo to Step 10Go to Step 9
7Does the Heated O2 sensor voltage measure below
the specified value?0.3VGo to Step 11Go to Step 8
8Check the Heated O2 sensor ground circuit, termi-
nal 3 for an open or poor connection and repair as
necessary.
Is repair necessary?–Go to Step 12Go to Step 8
9Check the Heated O2 sensor signal circuit, terminal
4 for an open or poor connection and repair as nec-
essary.
Is repair necessary?–Go to Step 12Go to Step 8

ENGINE CONTROLS 1F – 155
DAEWOO V–121 BL4
StepNo Yes Value(s) Action
101. If disconnected, reconnect Heated O2 sensor
connector.
2. Using the scan tool, clear the 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 indicated that this diagnostic has
run and passed?–Go to Step 13Go to Step 2
111. Turn the ignition switch to LOCK.
2. Replace the Heated O2 sensor.
3. Road tests the vehicle.
4. Perform the diagnostic system check.
Is the replacement complete?–Go to Step 15–
121. Turn the ignition switch to LOCK.
2. Replace the ECM.
3. Road tests the vehicle.
4. Perform the diagnostic system check.
Is the replacement complete?–Go to Step 15–
13Check if any additional DTCs are set.
Are any DTCs displaced that have not been diag-
nosed?–Go to applica-
ble DTC tableSystem OK

1F – 156IENGINE CONTROLS
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P0141
REAR HEATED OXYGEN SENSOR HEATER
MALFUNCTION
Circuit Description
The engine control module (ECM) supplies a voltage of
about 450mm volts between the ECM terminals 14 and 16.
The oxygen (O2) sensor varies the voltage within a range
of about 1volt if the exhaust is rich, down to about 100mm
volts if the exhaust is lean. The O2 sensor is like an open
circuit and produces no voltage when it is below
360°C(600°F). An open O2 sensor circuit or a cold O2
sensor causes ”open loop” operation.
Conditions for Setting the DTC
S The heated O2 sensor heater resistance is less
than 0 W or greater than 160 W. (1.4L DOHC)
S The heated O2 sensor heater resistance is less
than 10 W or greater than 30 W. (1.6L DOHC)
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.S The coolant fan turns ON.
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
S Normal scan tool voltage varies between 0.1volts
and 0.9 volts while in closed loop.
S Inspect the oxygen (O2) sensor wire. The O2 sen-
sor may be positioned incorrectly and contacting
the exhaust manifold.
S Check for an intermittent ground in the wire be-
tween the O2 sensor and the engine control mod-
ule.
S Perform an injector 2alance test to determine if a
restricted fuel injector may be causing the lean con-
dition.
S Vacuum of crankcase leaks will cause a lean run-
ning condition.

ENGINE CONTROLS 1F – 157
DAEWOO V–121 BL4
S An exhaust manifold gasket leak of a cracked ex-
haust manifold may cause outside air to be pulled
into the exhaust and past the sensor.
DTC P0141 – Rear Heated Oxygen Sensor Heater Malfunction
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. Turn the ignition switch to LOCK.
2. Disconnect the Heated O2 sensor connector
and engine control module (ECM) connector.
3. Check the Heated O2 sensor heater wire be-
tween the Heated O2 sensor connector termi-
nal 3 and ECM connector terminal 16 for an
open or short to ground.
Is the problem found?–Go to Step 3Go to Step 4
31. Repair the wire of the connector terminal as
needed.
2. Clear the DTCs from the ECM.
3. Road tests the vehicle.
4. Perform the diagnostic system check.
Is the repair complete?–System OK–
41. Turn the ignition switch to LOCK.
2. Replace the Heated O2 sensor.
3. Road tests the vehicle.
4. Perform the diagnostic system check.
Is the replacement complete?–Go to Step 6–
5Check if any additional DTCs are set.
Are any DTCs displaced that have not been diag-
nosed?–Go to applica-
ble DTC tableSystem OK

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.

ENGINE CONTROLS 1F – 159
DAEWOO V–121 BL4
DTC P0171 – Fuel Trim System Too Lean
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. Install the scan tool to the Data Link Connector
(DLC).
2. Turn the ignition ON.
Are any component related Diagnostic Trouble
Codes (DTCs) set?–Go to
applicable DTC
tableGo to Step 3
3With the engine running, operate the vehicle until the
LOOP STATUS indicates closed.
Is the Long Term Fuel Trim value below the specified
value?27%Go to Step 4Go to Step 5
41. Turn the ignition switch ON, with the engine
OFF.
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.
Does the Long Term Fuel Trim value go below the
specified value while operating under the specified
conditions?27%Go to Step 16Go to Step 5
5Visually/physically check the following items:
S Vacuum hoses for splits, kinks and improper
connections.
S Crankcase ventilation oil/air separator for prop-
er installation.
S Exhaust system for corrosion, leaks, loose or
missing hardware.
S Oxygen sensor (O2S) is installed securely and
the pigtail harness is not contacting exhaust
manifold or engine.
S Fuel for excessive water, alcohol, or other con-
taminants.
S Engine Control Module (ECM) and sensor
grounds are clean, tight, and in their proper
locations.
Do any of the above checks isolate a condition re-
quiring repair?–Go to Step 7Go to Step 6
61. Disconnect the Manifold Absolute Pressure
(MAP) sensor electrical connector.
2. Operate the vehicle in Closed Loop while moni-
toring the Long Term Fuel Trim value.
Is the Long Term Fuel Trim value below the specified
value?27%Go to Step 15Go to Step 9
71. Repair the malfunction found in Step 5.
2. Recheck the Long Term Fuel Trim value while
operating the engine.
Is the Long Term Fuel Trim value below the specified
value?27%Go to Step 8Go to Step 9