Lamp DAEWOO LACETTI 2004 Service Repair Manual

ENGINE CONTROLS 1F – 543
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P1134
FRONT HEATED OXYGEN SENSOR (HO2S1)
TRANSITION RATIO
Circuit Description
The Engine Control Module (ECM) monitors the Front
Heated Oxygen Sensor (HO2S1) activity for 100 seconds
after closed loop and stoichiometric operation have been
established. During the monitoring period the ECM counts
the number of times that the HO2S1 responds from rich
to lean and adds the amount of time it took to complete all
transitions. With this information, an average time for all
transitions can be determined. The ECM then divides the
–to–lean average by the lean–to–rich average to obtain
the ratio. If the HO2S1 transition time ratio is not within the
range, Diagnostic Trouble Code (DTC) P1134 will be set,
indicating that the HO2S1 is not responding as expected
to changes in exhaust oxygen content.
Conditions for Setting the DTC
S HO2S1 rich–to–lean and lean–to rich transition ratio
is out of specification(between 0.375 and 3.5).
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 Engine speed is between 1600 and 4300 rpm.
S Calculated 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, P1404, P0405, P0406,
P0506, P0507, 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.
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.
S A history DTC will clear after 40 consecutive warm–
up cycles without a fault.

1F – 546IENGINE CONTROLS
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P1167
FRONT HEATED OXYGEN SENSOR (HO2S1) RICH IN
DECEL FUEL CUTOFF (DFCO)
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.
In internal circuitry of the Engine control Module (ECM)
can identify if the vehicle fuel system is capable of cutoff
amount of the fuel supply during deceleration. When a De-
cel Fuel Cutoff (DFCO) mode of operation is requested
during Closed Loop operation, the ECM will cutoff the fuel
supply to the engine. Under these conditions the ECM
should detect a lean condition. If the ECM detect a rich
condition at this time, Diagnostic Trouble Code (DTC)
P1167 will set. Damaged fuel pressure regulator and faulty
injector will be the cause of this DTC.
Conditions for Setting the DTC
S HO2S1 voltage is greater than 0.55 volts in Decel
Fuel Cutoff (DFCO) mode.
S System voltage is greater than 10 volts.S Engine Coolant Temperature (ECT) is greater than
60°C (140°F)
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 in DFCO mode.
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.
S A history DTC will clear after 40 consecutive warm–
up cycles without a fault.
S DTC can be cleared by using the scan tool.

1F – 548IENGINE CONTROLS
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P1171
FUEL TRIM SYSTEM LEAN DURING POWER
ENRICHMENT
System Description
The internal circuitry of the Engine control Module (ECM)
can identify if the vehicle fuel system is capable of supply-
ing adequate amounts of fuel during heavy acceleration(
power enrichment). When a Power Enrichment (PE)
mode of operation is requested by heavy acceleration dur-
ing Closed Loop operation, the ECM will provide more fuel
to the engine. Under these conditions the ECM should de-
tect a rich condition. If this reich condition is nor detected
at this time, Diagnostic Trouble Code (DTC) P1171 will set.
A plugged fuel filter or restricted fuel line can prevent ade-
quate amount of fuel from being supplied during Power
Enrichment mode.
Conditions for Setting the DTC
S HO2S1 voltage is less than 0.35 volts in Power En-
richment (PE) mode.
S Engine is operating in Closed Loop and in PE
mode.
S Engine Coolant Temperature (ECT) is greater than
60°C (140°F).
S System voltage is greater than 10 volts.
S Air/Fuel ration is less than 13.5:1.
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 in PE mode.
Action Taken When the DTC Sets
S The Malfunction Indicator Lamp (MIL) will illuminate
after two 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 DTC is stored.
S The vehicle will operate in Open Loop.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.
S Disconnecting the ECM battery feed for more than
10 seconds.v
Diagnostic Aids
A restricted fuel filter can supply adequate amounts of fuel
at idle, but may not be able to supply enough fuel during
heavy acceleration.
Water or alcohol n fuel may cause low HO2S1 voltage dur-
ing acceleration.
Check for adequate amount of fuel in the Tank.
When the engine is idling or at steady cruise, the HO2S1
voltage should vary from between approximately a00 to
900 millivolts. During power enrichment mode, more fuel
is needed, and the HO2S1 should rise above 444 milli-
volts.
Check for faulty or plugged injector(s).
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.
4. This step checks to see if the HO2S1 is operating
properly.
6. If no faults have been found at this point and no
additional DTCs were set, refer to ”Diagnostic Aids”
in this section for additional checks and informa-
tion.

1F – 550IENGINE CONTROLS
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P1336
58X CRANK POSITION TOOTH ERROR NOT LEARNED
Circuit Description
In order to detect engine misfire at higher engine speeds,
the Engine Control Module (ECM) must know of any varia-
tion between the crankshaft sensor pulses. Most varia-
tions are due to the machining of the crankshaft reluctor
wheel. However, other sources of variation are also pos-
sible. A Crankshaft Position (CKP) system variation learn-
ing procedure must be performed any time a change is
made to the crankshaft sensor to crankshaft relationship
of if the ECM is replaced or reprogrammed. The ECM
measures the variations and then calculates compensa-
tion factors needed to enable the ECM to accurately de-
tect engine misfire at all speeds and loads. A scan tool
must be used to command the ECM to learn these varia-
tions. If for any reason the ECM is unable to learn these
variations or they are out of an acceptable range, the ECM
will set Diagnostic Trouble Code (DTC) P1336. An ECM
that has not had the CKP system variation learning proce-
dure performed due to replacement or reprogramming will
also set DTC P1336.
Conditions for Setting the DTC
S Tooth error not learned if the manufacture enable
counter is set to zero.
S DTCs P0106, P0107, P0108, P0117, P0118,
P0122, P0123, P0132, P0201, P0202, P0203,
P0204, P0325 , 0327, P0336, P0337, P0341,
P0342, P0351, P0352, P0402, P1404, P0404,
P0405, P0406 and P0502 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
buffer.
S A history DTC is stored.
Conditions for Clearing the MIL/DTC
S The MIL will turn OFF after four consecutive igni-
tion 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 Disconnecting the ECM battery feed for more than
10 seconds.
S DTC(s) can be cleared by using the scan tool.Diagnostic Aids
CAUTION : To avoid personal injury when performing
the crankshaft position system variation learning
procedure, always set the vehice parking brake and
block the drive wheels. Release the throttle immedi-
ately when the engine starts to decelerate. Once the
learn procedure is completed, engine control will be
returned to the operator, and the engine will respond
to throttle position.
DTC P1336 will only set if the ECM has not learned the
CKP system variation. The ECM only needs to learn this
variation once per life cycle of the vehicle unless the crank
sensor to crankshaft relationship is disturbed. Removing
a part is considered a disturbance. A fully warmed engine
is critical to learning the variation correctly. If a valid learn
occurs, no other learns can be completed that ignition
cycle.
If the engine cuts out before the specified learn procedure
engine speed or at normal fuel cutoff rpm, the ECM is not
in the learn procedure mode.
Test Description
The number(s) below refer to step(s) on the diagnostic
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 fault occurred. The information is then stored on
the scan tool for later reference.
2. Engine temperature is critical to properly learn the
CKP system variation. Failure to properly warm the
engine before performing this procedure will result
in an inaccurate measurement of the CKP system
variation. The ECM learns this variation as the en-
gine is decelerating and then allows engine control
to be returned to the operator. All accessories must
be OFF when learning the CKP system angle varia-
tion. If the A/C is not disabled when the learn pro-
cedure is enabled, the ECM will disable the A/C.
3. If after the specified number attempts the ECM
cannot learn the CKP system variation, then the
variation is too large and no further attempts should
be made until the variation problem is corrected.
4. Being unable to learn the procedure indicates that
the variation is out of range.
5. After the CKP system variation has been learned,
wait above 10 seconds with ignition switch OFF to
prevent being cleared the learned value.

1F – 552IENGINE CONTROLS
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P1391
G SENSOR ROUGH ROAD RATIONALITY
Circuit Description
TThe Gravity Sensing Rough Road (G) sensor is a vertical
low g–acceleration sensor. By sensing vertical accelera-
tion caused by bumps or potholes in the road, the Engine
Control Module (ECM) can determine if the changes in
crankshaft speed are due to engine misfire or are driveline
induced. If the G sensor detects a rough road condition,
the ECM misfire detection diagnostic will be de–activated.
The G sensor at rest output should be between 2.35–2.65
volts (+1G). During a rough road condition, the voltage
output can vary between 0.5 (–1G) and 4.5 volts (+3G).
Conditions for Setting the DTC
S Engine is running.
S Vehicle speed is less than or equal to 5 km/h (3.1
mph).
S G sensor output at idle indicates below –0.39 volts
or above 2.21 volts.
OR
S Engine is running more than 10 seconds and ve-
hicle speed is between 30 mph (50 km/h) and 70
mph (112 km/h).
S G sensor signal changes less than 0.00024 volts
while driving.
Action Taken When the DTC Sets
S The Malfunction Indicator Lamp (MIL) will not 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.Conditions for Clearing the MIL/DTC
S A history Diagnostic Trouble Code (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
Check for the following conditions:
S Poor connection at the ECM – Inspect the harness
connections for backed–out terminals, improper
mating, broken locks, improperly formed or dam-
aged terminals, and poor terminal–to–wire connec-
tion.
S Damaged harness –– Inspect the wiring harness for
damage. If the harness appears to be OK, observe
the G sensor display on the scan tool while moving
connectors and wiring harnesses related to the sen-
sor. A change in the display will indicate the loca-
tion of the fault.
Since the G sensor shares the ECM 5 volt reference and
ground terminals with the A/C Pressure Sensor, a dam-
aged A/C Pressure Sensor harness or sensor could cause
a G sensor DTC to set. Refer to ”Multiple ECM Information
Sensor DTCs Set” in this section. in this section.
The G sensor will give correct voltages only if it is level and
mounted securely to its bracket.
Reviewing the Failure Records vehicle mileage since the
diagnostic test last failed may help determine how often
the condition that caused the DTC to be set occurs. This
may assist in diagnosing the con

ENGINE CONTROLS 1F – 555
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P1392
G SENSOR ROUGH ROAD LOW VOLTAGE
Circuit Description
The Gravity Sensing Rough Road (G) sensor is a vertical
low g–acceleration sensor. By sensing vertical accelera-
tion caused by bumps or potholes in the road, the Engine
Control Module (ECM) can determine if the changes in
crankshaft speed are due to engine misfire or are driveline
induced. If the G sensor detects a rough road condition,
the ECM misfire detection diagnostic will be de–activated.
The G sensor at rest output should be between 2.35–2.65
volts (+1G). During a rough road condition, the voltage
output can vary between 0.5 (–1G) and 4.5 volts (+3G).
Conditions for Setting the DTC
S G sensor output is less than 2%.
S Engine is running more than or equal to 10 sec-
onds.
Action Taken When the DTC Sets
S The Malfunction Indicator Lamp (MIL) will not 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.
Conditions for Clearing the MIL/DTC
S A history Diagnostic Trouble Code (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
Check for the following conditions:S Poor connection at the ECM – Inspect the harness
connections for backed–out terminals, improper
mating, broken locks, improperly formed or dam-
aged terminals, and poor terminal–to–wire connec-
tion.
S Damaged harness – Inspect the wiring harness for
damage. If the harness appears to be OK, observe
the G sensor display on the scan tool while moving
connectors and wiring harnesses related to the sen-
sor. A change in the display will indicate the loca-
tion of the fault.
Since the G sensor shares the ECM 5 volt reference and
ground terminals with the A/C Pressure Sensor, a dam-
aged A/C Pressure Sensor harness or sensor could cause
a G sensor DTC to set. Refer to ”Multiple ECM Information
Sensor DTCs Set” in this section.
The G sensor will give correct voltages only if it is level and
mounted securely to its bracket.
Reviewing the Failure Records vehicle mileage since the
diagnostic test last failed may help determine how often
the condition that caused the DTC to be set occurs. This
may assist in diagnosing the condition.
Test Description
The number(s) below refer to step(s) on the diagnostic
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.

1F – 558IENGINE CONTROLS
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P1393
G SENSOR ROUGH ROAD HIGH VOLTAGE
Circuit Description
The Rough Road (G) sensor is a vertical low g–accelera-
tion sensor. By sensing vertical acceleration caused by
bumps or potholes in the road, the Engine Control Module
(ECM) can determine if the changes in crankshaft speed
are due to engine misfire or are driveline induced. If the G
sensor detects a rough road condition, the ECM misfire
detection diagnostic will be de–activated. The G sensor at
rest output should be between 2.35–2.65 volts (+1G). Dur-
ing a rough road condition, the voltage output can vary be-
tween 0.5 (–1G) and 4.5 volts (+3G).
Conditions for Setting the DTC
S G sensor output is greater than 98%.
S Engine is running more than or equal to 10 sec-
onds.
Action Taken When the DTC Sets
S The Malfunction Indicator Lamp (MIL) will not 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.
Conditions for Clearing the MIL/DTC
S A history Diagnostic Trouble Code (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
Check for the following conditions:S Poor connection at the ECM – Inspect the harness
connections for backed–out terminals, improper
mating, broken locks, improperly formed or dam-
aged terminals, and poor terminal–to–wire connec-
tion.
S Damaged harness – Inspect the wiring harness for
damage. If the harness appears to be OK, observe
the G sensor display on the scan tool while moving
connectors and wiring harnesses related to the sen-
sor. A change in the display will indicate the loca-
tion of the fault.
Since the G sensor shares the ECM 5 volt reference and
ground terminals with the A/C Pressure Sensor, a dam-
aged A/C Pressure Sensor harness or sensor could cause
a G sensor DTC to set. Refer to”Multiple ECM Information
Sensor DTCs Set” in this section.
The G sensor will give correct voltages only if it is level and
mounted securely to its bracket.
Reviewing the Failure Records vehicle mileage since the
diagnostic test last failed may help determine how often
the condition that caused the DTC to be set occurs. This
may assist in diagnosing the condition.
Test Description
The number(s) below refer to step(s) on the diagnostic
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.

ENGINE CONTROLS 1F – 561
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P1396
ABS WSS SIGNAL VARIATION
Circuit Description
The Engine Control Module (ECM) determines linear
wheel speed excessive variation. The wheel speed varia-
tion test detects at least one missing edge from the wheel
speed sensor signal.
Conditions for Setting the DTC
S WSS variation is greater than 18km/h (11.2 mph).
S Vehicle speed is greater than 10km/h (6.2 mph).
Action Taken When the DTC Sets
S The Malfunction Indicator Lamp (MIL) will not illumi-
nate.
S The ECM will store conditions which were present
when the DTC set as Failure Records data only.
This information will not be stored as Freeze Frame
data.
S A history DTC is stored.
Conditions for Clearing the MIL/DTC
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.
Diagnostic Aids
Check for the following conditions:S Poor connection at the ECM – Inspect the harness
connections for backed–out terminals, improper
mating, broken locks, improperly formed or dam-
aged terminals, and poor terminal–to–wire connec-
tion.
S Damaged harness – Inspect the wiring harness for
damage. If the harness appears to be OK, observe
the G sensor display on the scan tool while moving
connectors and wiring harnesses related to the sen-
sor. A change in the display will indicate the loca-
tion of the fault.
An open signal circuit of open PWM serial data line be-
tween the ECM and the EBCM will be the cause of this
DTC.
Test Description
The number(s) below refer to specific step(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.
6. The replacement ECM must be reprogrammed.
Refer to the latest Techline procedure for ECM re-
programming.

ENGINE CONTROLS 1F – 563
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P1397
ABS WSS NO SIGNAL
Circuit Description
The Engine Control Module (ECM) determines linear
wheel speed fail threshold. The ECM detects a good or
failed wheel speed sensor under power conditions.
Conditions for Setting the DTC
S Vehicle speed is greater than 10km/h (6.2 mph).
Action Taken When the DTC Sets
S The Malfunction Indicator Lamp (MIL) will not illumi-
nate.
S The ECM will store conditions which were present
when the DTC set as Failure Records data only.
This information will not be stored as Freeze Frame
data.
S A history DTC is stored.
Conditions for Clearing the MIL/DTC
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.
Diagnostic Aids
Check for the following conditions:S Poor connection at the ECM – Inspect the harness
connections for backed–out terminals, improper
mating, broken locks, improperly formed or dam-
aged terminals, and poor terminal–to–wire connec-
tion.
S Damaged harness – Inspect the wiring harness for
damage. If the harness appears to be OK, observe
the G sensor display on the scan tool while moving
connectors and wiring harnesses related to the sen-
sor. A change in the display will indicate the loca-
tion of the fault.
An open signal circuit of open PWM serial data line be-
tween the ECM and the EBCM will be the cause of this
DTC.
Test Description
The number(s) below refer to specific step(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.
6. The replacement ECM must be reprogrammed.
Refer to the latest Techline procedure for ECM re-
programming.

ENGINE CONTROLS 1F – 565
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P1404
EXHAUST GAS RECIRCULATION CLOSED VALVE
PINTLE ERROR
Circuit Description
An Exhaust Gas Recirculation (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/fuelmixture 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 an En-
gine Control Module (ECM) controlled pintle. The ECM
controls the pintle position using inputs from the Throttle
Position (TP) and Manifold Absolute Pressure (MAP) sen-
sors. 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 De-
sired 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.
Conditions for Setting the DTC
S Difference between current and learned low posi-
tion is greater than 10%.S Desired EGR position is equal to 0.
S Engine is running.
S Ignition voltage is between 11.7 and 16 volts.
S Intake Air Temperature (IAT) is greater than 3°C
(37.4°F).
S DTCs P0112, P0113, P0405, P0406, and P0502
are not set.
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 fails. This information will be
stored in the Freeze Frame and Failure Records
buffers.
S A history Diagnostic Trouble Code (DTC) is stored.
S EGR is disabled.
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 80 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
Due to moisture associated with exhaust systems, the
EGR valve may freeze and stick in cold weather. After the
vehicle is brought into a warm shop for repairs, the valve
warms and the problem disappears. By watching the Actu-
al EGR and Desired EGR Positions on a cold vehicle with
a scan tool, the fault can be easily verified. Check the