acc DAEWOO LACETTI 2004 Service Owners Manual

ENGINE CONTROLS 1F – 481
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P0406
EXHAUST GAS RECIRCULATION PINTLE POSITION HIGH
VOLTAGE
Circuit Description
An Exhaust Gas Recirculation (EGR) system is used to
lower Nitrogen Oxide (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 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. This diagnostic Trouble Code (DTC) will detect
short circuit.Conditions for Setting the DTC
S EGR position signal is greater than 98%.
S Ignition voltage is between 11.7 and 16 volts.
S Fail condition last more than 10 seconds.
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 Diagnostic Trouble Code (DTC) is stored.
S EGR is disabled.
Conditions for Clearing the MIL/DTC
S The MIL will turns 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
Due to moisture associated with exhaust systems, the
EGR valve may freeze and stick in cold weather at times.
After the vehicle is brought into a warm shop for repairs,
the valve warms and the problem disappears. By watching
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).

1F – 482IENGINE 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. Commanding the EGR valve open determines
whether the EGR system can control the EGR
valve accurately and if the fault is present.
3. If the EGR valve 5 volt reference is shorted to
ground, the digital voltmeter (DVM) will read no
voltage and additional DTCs may be set and the
engine performance will be poor. When this circuit
is open, only a DTC P0405 will be set.
4. Jumpering the 5 volt reference circuit to the signal
circuit checks the signal circuit and the ECM. The
scan tool should display the Actual EGR Position
as 100% if the signal circuit and ECM are OK.
6. Although the ECM and circuitry acted correctly in
the previous step, a problem may still lie within the
terminals which would not show up in probe typetesting. Be sure to check the terminals for being
backed out, improperly formed or damaged, and for
poor tension.
10. 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.
12. The replacement ECM must be reprogrammed.
Refer to the latest Techline procedure for ECM re-
programming.
13. Check the terminals for being backed out, improp-
erly formed or damaged, and for poor tension.
14. 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 an EGR command, the new
pintle will not be learned.
15. 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 P0406 – Exhaust Gas Recirculation Pintle Position High
Voltage
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. Install a scan tool to the Data Link Connector
(DLC).
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 14Go to Step 3
31. Turn the ignition OFF.
2. Disconnect the EGR valve.
3. Turn the ignition ON.
4. With 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 4Go to Step 5
4Jumper the 5 volt reference circuit to the signal cir-
cuit at terminal 4 and C at the EGR valve wiring har-
ness connector.
Does the Actual EGR Position display the specific
value?100%Go to Step 6Go to Step 7

1F – 498IENGINE CONTROLS
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P0502
VEHICLE SPEED SENSOR NO SIGNAL (ENGINE SIDE)
Circuit Description
Vehicle speed information is provided to the Engine Con-
trol Module (ECM) by the Vehicle Speed Sensor (VSS).
The VSS is a permanent magnet generator that is
mounted in the transaxle and produces a pulsing voltage
whenever vehicle speed is over 3 mph (5 km/h). The Alter-
nating Current (AC) voltage level and the number of
pulses increases with vehicle speed. The ECM converts
the pulsing voltage into mph (km/h) and then supplies the
necessary signal to the instrument panel for speedometer/
odometer operation and to the cruise control module and
multi–function alarm module operation. This Diagnostic
Trouble Code (DTC) will detect if vehicle speed is reason-
able according to engine rpm and load.
Conditions for Setting the DTC
S Vehicle speed is less than 5 km/h (3.1 mph) for
Power and Decel test.
S Engine is running.
S Engine Coolant Temperature (ECT) is greater than
60 °C (140 °F).
S Ignition voltage is between 11–16 volts.
S Power Test
S The rpm is between 1200 and 4000.S Throttle Position (TP) sensor is between 25%
and 60%.
S MAP is greater than 60 kPa (8.7 psi).
S Deceleration Test
S Generator compensated Manifold Absolute
Pressure (MAP) is less than 30 kPa (4.4 psi)
S Change in rpm per cycle is less than 50 rpm/
cycle.
S Throttle Position (TP) sensor is less than 0.8%.
S The rpm is between 1800 and 6000.
S DTC(s) P0106, P0107, P0108, P0117, P0118,
P0122, P0123, P0201, P0202, P0203, P0204,
P0300, P0351, P0352, P0402, P0404, P1404,
P0405, and P0406 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 DTC is stored.
Conditions for Clearing the MIL/DTC

ENGINE CONTROLS 1F – 501
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P0506
IDLE SPEED RPM LOWER THAN DESIRED IDLE SPEED
Circuit Description
The Engine Control Module (ECM) controls the air enter-
ing into the engine with an Idle Air Control (IAC) Valve. To
increase the idle rpm, the ECM commands the pintle in-
side the IAC valve away from the throttle body seat. This
allows more air to bypass through the throttle blade. To de-
crease the rpm the ECM commands the pintle towards the
throttle body seat. This reduces the amount of air bypass-
ing the throttle blade. A scan tool will read the IAC valve
pintle position in counts. The higher the counts, the more
air that is allowed to bypass the throttle blade. This Diag-
nostic Trouble Code (DTC) determines if a low idle condi-
tion exists as defined as 100 rpm below the desired idle
rpm.
Conditions for Setting the DTC
S No intrusive tests are active.
S DTC(s) P0106, P0107, P0108, P0112, P0113,
P0117, P0118, P0122, P0123, P0131, P0132,
P0133, P0135, P0141, P1133, P1134, P0171,
P01167, P1171, P0172, P0201, P0202, P0203,
P0204, P0300, P0336, P0337, P0341, P0342,
P0351, P0352, P0402, P0404, P1404, P0405,
P0406, P0443, and P0502 are not set.
S Engine is running more than 60 seconds.
S Barometric Pressure (BARO) is greater than 72
kPa (10.4 psi).
S Engine Coolant Temperature (ECT) is greater than
60°C (140°F).
S Ignition voltage is between 11 and 16 volts.
S Manifold Absolute Pressure is less than 60 kPa (8.7
psi).
S IAC valve is controlled fully opened.
S All of the above must be met for greater than 5 sec-
onds.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.
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
Inspect the IAC valve electrical connection for proper mat-
ing.
Inspect the wiring harness for damage.
Inspect the throttle stop screw for signs of tampering.
Inspect the throttle linkage for signs of binding or exces-
sive wear.
A slow or unstable idle may be caused by one of the follow-
ing conditions:
S Fuel system too rich or too lean.
S Foreign material in the throttle body bore or in the
air induction system.
S A leaking or restricted intake manifold.
S Excessive engine overloading. Check for seized
pulleys, pumps, or motors on the accessory drive.
S Overweight engine oil.

ENGINE CONTROLS 1F – 505
DAEWOO V–121 BL4
S Fuel system too rich or too lean.
S Foreign material in the throttle body bore or in the
air induction system.
S A leaking or restricted intake manifold.
S Excessive engine overloading. Check for seized
pulleys, pumps, or motors on the accessory drive.
S Overweight engine oil.
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, broken
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 for additional checks and information.
DTC P0507 – Idle Speed RPM Higher 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

ENGINE CONTROLS 1F – 513
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P0562
SYSTEM VOLTAGE TOO LOW (ENGINE SIDE)
Circuit Description
The Engine Control Module (ECM) monitors the ignition
voltage on the ignition feed circuit to terminal K18 at the
ECM. A system voltage Diagnostic Trouble Code (DTC)
will set whenever the voltage is below a calibrated value.
Conditions for Setting the DTC
S System voltage is less than 11 volts.
S Engine is running.
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 Failure Records buffers.
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 DTC(s) can be cleared by using the scan tool.
S Disconnecting the ECM battery feed for more than
10 seconds.
Diagnostic Aids
If the DTC sets when an accessory is operated, check for
a poor connection or excessive current draw.
Any circuitry, that is suspected as causing the intermittent
complaint, should be thoroughly checked for the following
conditions:S Backed–out terminals
S Improper mating
S Broken locks
S Improperly formed
S Damaged terminals
S Poor terminal–to–wiring connections
S Physical damage to the wiring 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 checks if the generator is malfunctioning under
load conditions.
4. Checks the ignition feed circuit for excessive resist-
ance. An open circuit will cause a no start condi-
tion.
7. The replacement ECM must be reprogrammed.
Refer to the latest Techline procedure for ECM re-
programming.
9. 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 for additional checks and information.

ENGINE CONTROLS 1F – 515
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P0563
SYSTEM VOLTAGE TOO HIGH (ENGINE SIDE)
Circuit Description
The Engine Control Module (ECM) monitors the ignition
voltage on the ignition feed circuit to terminal K18 at the
ECM. A system voltage Diagnostic Trouble Code (DTC)
will set whenever the voltage is above a calibrated value.
Conditions for Setting the DTC
S System voltage is less than 16 volts.
S Engine is running.
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 Failure Records buffers.
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 DTC(s) can be cleared by using the scan tool.
S Disconnecting the ECM battery feed for more than
10 seconds.
Diagnostic Aids
If the DTC sets when an accessory is operated, check for
a poor connection or excessive current draw.Any circuitry, that is suspected as causing the intermittent
complaint, should be thoroughly checked for the following
conditions:
S Backed–out terminals
S Improper mating
S Broken locks
S Improperly formed
S Damaged terminals
S Poor terminal–to–wiring connections
S Physical damage to the wiring 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 checks if the generator is malfunctioning under
load conditions.
7. The replacement ECM must be reprogrammed.
Refer to the latest Techline procedure for ECM re-
programming.
9. 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 for additional checks and information.

1F – 540IENGINE CONTROLS
DAEWOO V–121 BL4
Diagnostic Aids
DTC P1133 is most likely caused by one of the following
items:
S Fuel Pressure – The system will go rich if the fuel
pressure is too high. The ECM can compensate for
some increase. However, if it gets too high, a DTC
P1133 may set. Refer to ”Fuel System Diagnosis”
in this section.
S Leaking injector – A leaking or malfunctioning injec-
tor can cause the system to go rich.
S Manifold Absolute Pressure (MAP) sensor – An
output that causes the ECM to sense a higher than
normal manifold pressure (low vacuum) can cause
the system to go rich. Disconnecting the MAP sen-
sor will allow the ECM to set a fixed value for the
MAP sensor. Substitute a different MAP sensor if
the rich condition is gone while the sensor is dis-
connected.
S Pressure regulator – Check for a leaking fuel pres-
sure regulator diaphragm by checking for the pres-
ence of liquid fuel in the vacuum line to the pres-
sure regulator.
S Throttle Position (TP) sensor – An intermittent TP
sensor output can cause the system to go rich due
to a false indication of the engine accelerating.S HO2S1 contamination – Inspect the HO2S1 for sili-
cone contamination from fuel or improper use of
Room Temperature Vulcanizing (RTV) sealant. The
sensor may have a white powdery coating and re-
sult in a high but false voltage signal (rich exhaust
indication). The ECM will then reduce the amount
of fuel delivered to the engine causing a severe
surge or driveability problem.
Test Description
Number(s) below refer to the step number(s) on the Diag-
nostic Chart.
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.
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 are set, refer to ”Diagnostic
Aids” in this section for additional checks and infor-
mation.
DTC P1133 – Front Heated Oxygen Sensor (HO2S1) Too Few
Transition
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.
Are any additional Diagnostic Trouble Codes
(DTCs) set?–Go to
applicable DTC
tableGo to Step 3
31. Start the engine and idle at normal operating
temperature.
2. Operate the vehicle within the specified param-
eter under the Conditions For Setting the DTC.
3. Monitor the lean–to–rich transition and rich–to–
lean transition and note the number of
switches.
Does the parameter show fewer transitions than the
specified value within 90 seconds.15Go to Step 4Go to Step 18

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.

ENGINE CONTROLS 1F – 549
DAEWOO V–121 BL4
DTC P1171 – Fuel Trim Supply System Lean During Power
Enrichment
StepActionValue(s)YesNo
1Perform an On–Board Diagnostic (EOBD) System
Check.
Is the system check complete?–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.
Are any component related Diagnostic Trouble
Codes (DTCs) set?–Go to
applicable DTC
tableGo to Step 3
31. Check the vehicle for an adequate amount of
fuel.
2. Add fuel to the vehicles fuel tank if the tank is
almost empty.
Did the fuel tank require fuel?–Go to Step 5Go to Step 4
41. Using a scan tool, observe the Front Heated
Oxygen Sensor (HO2S1) voltage while acceler-
ating the engine over 1200 rpm.
2. The HO2S1 voltage should vary from specified
voltage (100––900 mV) and occasionally toggle
above the specified voltage while accelerating.
Is the HO2S1 voltage toggle?3507 mVGo to
”Fuel System
Diagnosis”Go to
”DTC P0134
Oxygen Sensor
No Activity”
51. 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 6Go to Step 2
6Check if any additional DTCs are set.
Are any DTCs displayed that have not been diag-
nosed?–Go to
Applicable DTC
tableSystem OK