2004 DAEWOO LACETTI speed sensor

1F – 358IENGINE CONTROLS
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P0113
INTAKE AIR TEMPERATURE HIGH VOLTAGE
Circuit Description
The Intake Air Temperature (IAT) sensor uses a thermistor
to control the signal voltage to the Engine Control Module
(ECM). The ECM supplies a 5 volt reference and a ground
to the sensor. When the air is cold, the resistance is high;
therefore the IAT signal voltage will be high. If the intake
air is warm, resistance is low; therefore the IAT signal volt-
age will be low.
Conditions for Setting the DTC
S IAT is less than –38°C (–36°F).
S Vehicles speed is less than 25 km/h (16 mph).
S Engine run time is greater than 120 seconds.
S Engine Coolant Temperature (ECT) is above 70 °C
158 °F).
S Calculated air are flow is less than 15 g/second.
S DTC P0502, P0117, P0118 not set.
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 ECM will substitute a default value for intake
air temperature. The scan tool will not show the
defaulted value.
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
S If the vehicle is at ambient temperature, compare
the IAT sensor to the Engine Coolant Temperature
(ECT) sensor. The IAT sensor and the ECT sensor
should be relatively close to each other.
S Use the Temperature vs. Resistance Values table
to evaluate the possibility of a skewed sensor. Re-
fer to ”Temperature vs. Resistance” in this section.
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 simulates a DTC P0112. If the ECM
senses the change, the ECM and wiring are OK.
5. This step will determine if the reason the ECM did
not sense the change was due to a open ground or
signal circuit or malfunctioning ECM.
11. The replacement ECM must be reprogrammed.
Refer to the latest Techline procedure for ECM re-
programming.

1F – 366IENGINE CONTROLS
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P0122
THROTTLE POSITION SENSOR LOW VOLTAGE
Circuit Description
The Engine Control Module (ECM) supplies a 5 volt refer-
ence voltage signal and a ground to the Throttle Position
(TP) sensor. The TP sensor sends a voltage signal back
to the ECM relative to the throttle plate opening. The volt-
age signal will vary from approximately 0.33 volts at closed
throttle, to over 4.3 volts at Wide Open Throttle (WOT).
The TP signal is used by the ECM for fuel control and for
most of the ECM controlled outputs. The TP signal is one
of the most important inputs used by the ECM for fuel con-
trol and most of the ECM controlled outputs.
Conditions for Setting the DTC
S TP sensor voltage indicates a throttle voltage less
than 0.14 volts.
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 TP angle will default to 0% when the vehicle
speed is less than 3 km/h (2 mph) and 10% when
the vehicle speed is greater than 3 km/h (2 mph).
The scan tool will not display the default value.
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
If the DTC P0122 cannot be duplicated, the information in-
cluded in the Freeze Frame data can be useful. Use a scan
tool information data to determine the status of the DTC.
If the dc occurs intermittently, using the Diagnostic table
may help isolate the problem.
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. The TP sensor has an auto zeroing feature. If the
voltage reading is between 0.2 to 0.9 volts, the
ECM will assume the TP sensor is at a closed
throttle position (0%).
5. Simulates a high voltage signal which will identify
an open in the signal circuit.
6. If additional DTCs are set, check the 5v reference
circuits for a short to ground.
8. If the test light illuminates while probing the TP sig-
nal circuit, then the TP signal circuit is shorted to
ground.
11. The replacement ECM must be reprogrammed.
Refer to the latest Techline procedure for ECM re-
programming.

ENGINE CONTROLS 1F – 369
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P0123
THROTTLE POSITION SENSOR HIGH VOLTAGE
Circuit Description
The Engine Control Module (ECM) supplies a 5 volt refer-
ence voltage signal and a ground to the Throttle Position
(TP) sensor. The TP sensor sends a voltage signal back
to the ECM relative to the throttle plate opening. The volt-
age signal will vary from approximately 0.33 volts at closed
throttle, to over 4.3 volts at Wide Open Throttle (WOT).
The TP signal is used by the ECM for fuel control and for
most of the ECM controlled outputs. The TP signal is one
of the most important inputs used by the ECM for fuel con-
trol and most of the ECM controlled outputs.
Conditions for Setting the DTC
S TP sensor voltage indicates a throttle voltage great-
er than 4.9 volts.
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 TP angle will default to 0% when the vehicle
speed is less than 3 km/h (2 mph) and 10% when
the vehicle speed is greater than 3 km/h (2 mph).
The scan tool will not display the default value.
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
If the DTC P0123 cannot be duplicated, the information in-
cluded in the Freeze Frame data can be useful. Use a scan
tool information data to determine the status of the DTC.
If the dc occurs intermittently, using the Diagnostic table
may help isolate the problem.
With ignition ON and the throttle at closed position, the
voltage should read between 0.2 and 0.90 volts and in-
crease steadily to over 4.3 volts at WOT.
DTCs P0123 and P0113 stored at the same time could be
result of an open sensor ground circuit.
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. With the throttle closed, the TP sensor voltage
should read less than 0.90 volts. If the TP sensor
voltage does not read less than 0.90 volts check for
a binding or sticking throttle cable.
4. With the TP sensor disconnected, the TP sensor
voltage should be less than 0.2 volts if the ECM
and wiring are OK.
5. Probing the ground circuit with a test light checks
the circuit for high resistance which will cause a
DTC P0123 to set.

ENGINE CONTROLS 1F – 373
DAEWOO V–121 BL4
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 The DTC(s) can be cleared by using the scan tool.
S Disconnecting the ECM battery feed for more than
10 seconds.
Diagnostic Aids
S Fuel pressure – The system will be lean if the fuel
pressure is too low. It may be necessary to monitor
the fuel pressure while driving the vehicle at various
road speeds and/or loads to confirm. Refer to ”Fuel
System Diagnosis” in this section.
S Manifold Absolute Pressure (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. Disconnecting the MAP sen-
sor will allow the ECM to substitute a fixed (default)
value for the MAP sensor. If the lean condition is
gone when the sensor is disconnected, 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 P0131.
S Sensor harness – The HO2S1 sensor pigtail may
be mis–positioned and contacting the exhaust man-
ifold.
S Engine misfire – A misfiring cylinder will result in
unburned oxygen in the exhaust, which could cause
DTC P0131 to set. Refer to DTC P0300 Engine
Misfire in this section.S Cracked Front Heated Oxygen Sensor – A cracked
HO2S1 or poor ground at the sensor could cause
DTC P0131. Refer to”Symptoms Diagnosis” in this
section.
S Plugged fuel filter – A plugged fuel filter can cause
a lean condition and cause a DTC P0131 to set.
S Plugged Front Heated Oxygen Sensor – A plugged
reference port on the HO2S1 will indicate a lower–
than–normal voltage output from the HO2S1.
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 step determines if DTC P0131 is the result of
a hard failure or an intermittent condition. It may be
necessary to operate the vehicle within the Freeze
Frame conditions and Conditions for Setting the
DTC in order to duplicate the malfunction detected
by the ECM.
4. This step simulates DTC P0134. If the ECM senses
the change, the ECM and the wiring are OK.
6. The replacement ECM must be reprogrammed.
Refer to the latest Techline procedure for ECM re-
programming.
8. If no malfunctions have been found at this point and
no additional DTCs were set, refer to ”Diagnostic
Aids” for additional checks and information.
DTC P0131 – Front Heated Oxygen Sensor (HO2S1) Low Voltage
StepActionValue(s)YesNo
1Perform an On–Board Diagnostic (EOBD) System
Check.
Is the check completed?–Go to Step 2Go to
”On–Board
Diagnostic Sys-
tem Check”
21. Install a scan tool to the Data Link Connector
(DLC).
2. Start the engine and idle at normal operating
temperature.
Does the Front Heated Oxygen Sensor (HO2S1)
voltage remain below the value specified?0.1 VGo to Step 4Go to Step 3
31. Review the Freeze Frame data and note the
parameters.
2. Operate the vehicle within the Freeze frame
conditions and Conditions For Setting the DTC
as noted.
Does the HO2S1 voltage stay below the specified
value?0.1 VGo to Step 4Go to Step 7

1F – 400IENGINE CONTROLS
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P0171
FUEL TRIM SYSTEM TOO LEAN
System Description
To provide the best possible combination of driveability,
fuel economy, and emission control, a Closed Loop air/fuel
metering system is used. While in Closed Loop, the En-
gine Control Module (ECM) monitors the Front Heated
Oxygen Sensor (HO2S1) signal voltage and adjusts fuel
delivery based on signal voltage. A change made to fuel
delivery will be indicated by the long and short term fuel
trim values which can be monitored with the scan tool.
Ideal fuel trim values are around 128 (0%). If the HO2S1
signal is indicating a lean condition, the ECM will add fuel
resulting in fuel trim values above 128 (0% to 100%). If a
rich condition is detected, the fuel trim values will be below
128 (0% to –100%), indicating that the ECM is reducing
the amount of fuel delivered. If exhaust emissions reach
an excessive level due to a lean or rich condition, a fuel
trim Diagnostic Trouble Code (DTC) is set.
Conditions for Setting the DTC
S The average of adaptive index multiplier value is
greater than 1.28.
S No intrusive tests active.
S DTCs P0106, P0107, P0108, P0112, P0113,
P0117, P0118, P0122, P0123, P0131, P0132,
P0133, P0134, P0135, P1167, P1171, P0300,
P0336, P0337, P0341, P0342, P0402, P0404,
P1404, P0405, P0406, P0443, P0506, and P0507
are not set.
S Throttle Position (TP) is less than 95%.
S Engine speed is between 700 and 6000 rpm.
S Barometric Pressure (BARO) is greater than 72.0
kPa (10.4 psi).
S Coolant temperature is between 70°C (158°F) and
11 5°C (239°F).
S Manifold Absolute Pressure (MAP) is between 25
kPa (3.6 psi) and 99.7 kPa (14.5 psi).
S Intake Air Temperature (IAT) is between –40°C
(–40°F) and 120°C (248°F).
S Airflow is between 1.5 and 45 g/sec.
S Vehicle speed is less than 140 km/h (87 mph).
S System is in closed loop.
S Adaptive index is ready.
S System voltage is greater than 11 volts.
Action Taken When the DTC Sets
S The Malfunction Indicator Lamp (MIL) will illuminate
after two consecutive ignitions cycle in which the
diagnostic runs with the fault active.
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 two consecutive ignition
cycles in which the diagnostic runs without a fault
within the freeze frame conditions that the DTC
failed.
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.
S Disconnecting the ECM battery feed for more than
10 seconds.
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 HO2S1 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 HO2S1 display on the scan
tool while moving the connectors and the wiring harness
related 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.
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-

1F – 402IENGINE CONTROLS
DAEWOO V–121 BL4
StepNo Yes Value(s) Action
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?25%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?25%Go to Step 8Go to Step 9
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 10
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”

1F – 404IENGINE CONTROLS
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P0172
FUEL TRIM SYSTEM TOO RICH
System Description
To provide the best possible combination of driveability,
fuel economy, and emission control, a Closed Loop air/fuel
metering system is used. While in Closed Loop, the En-
gine Control Module (ECM) monitors the Front Heated
Oxygen Sensor (HO2S1) signal voltage and adjusts fuel
delivery based on signal voltage. A change made to fuel
delivery will be indicated by the long and short term fuel
trim values which can be monitored with the scan tool.
Ideal fuel trim values are around 128 (0%). If the HO2S1
signal is indicating a lean condition, the ECM will add fuel
resulting in fuel trim values above 128 (0% to 100%). If a
rich condition is detected, the fuel trim values will be below
128 (0% to –100%), indicating that the ECM is reducing
the amount of fuel delivered. If exhaust emissions reach
an excessive level due to a lean or rich condition, a fuel
trim Diagnostic Trouble Code (DTC) is set.
Conditions for Setting the DTC
S The average of adaptive index multiplier value is
less than 0.75.
S No intrusive tests active.
S DTCs P0106, P0107, P0108, P0112, P0113,
P0117, P0118, P0122, P0123, P0131, P0132,
P0133, P0134, P0135, P1167, P1171, P0336,
P0337, P0341, P0342, P0402, P0404, P1404,
P0405, P0406, P0443, P0506, and P0507 are not
set.
S Throttle Position (TP) is less than 95%.
S Engine speed is between 700 and 6000 rpm.
S Barometric Pressure (BARO) is greater than 72.0
kPa (10.4 psi).
S Coolant temperature is between 70°C (158°F) and
11 5°C (239°F).
S Manifold Absolute Pressure (MAP) is between 25
kPa (3.6 psi) and 99.7 kPa (14.5 psi).
S Intake Air Temperature (IAT) is between –40°C
(–40°F) and 120°C (248°F).
S Airflow is between 1.5 and 45 g/sec.
S Vehicle speed is less than 140 km/h (87 mph).
S System is in closed loop.
S Adaptive index is ready.
S System voltage is greater than 11 volts.
Action Taken When the DTC Sets
S The Malfunction Indicator Lamp (MIL) will illuminate
after two consecutive ignitions cycle in which the
diagnostic runs with the fault active (SOHC).
S The Malfunction Indicator Lamp (MIL) will illuminate
after first consecutive ignitions cycle (DOHC).
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 two consecutive ignition
cycles in which the diagnostic runs without a fault
within the freeze frame conditions that the DTC
failed.
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.
S Disconnecting the ECM battery feed for more than
10 seconds.
Diagnostic Aids
Important : After repairs, use the scan tool Fuel Trim Re-
set function to reset the long–term fuel trim to 128 (0%).
Check for poor connection at the ECM. Inspect the har-
ness 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 HO2S1 display on the scan
tool while moving the connectors and the wiring harness
related to the engine harness. A change in the display will
indicate the location of the fault.
If a DTC P1404 is also set, check the 5 volt reference cir-
cuits for a short to voltage.
Check for a restricted exhaust system.
A shorted 5 volt reference circuit may cause a DTC P0172
to set. Check the 5 volt reference sensors for abnormal
readings.
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.
5. A clogged air cleaner filter element restricts the air-
flow coming into the engine. This step checks the
condition of the air cleaner filter.
17. A leaky injector can cause a rich condition and set
DTC P0172. Refer to ”Fuel Injector Balance Test”
in this section.
19. A loose TP sensor may not set a TP sensor related
DTC, but may cause the system to become rich by
a higher–than–actual TP reading.

1F – 406IENGINE CONTROLS
DAEWOO V–121 BL4
StepNo Yes Value(s) Action
111. Turn the ignition OFF.
2. Disconnect the Manifold Absolute Pressure
(MAP) sensor electrical connector.
3. Start the engine.
4. Operate the vehicle in Closed Loop while moni-
toring the Long Term Fuel Trim value.
Does the Long Term Fuel Trim value increase above
the specified value?–20%Go to Step 20Go to Step 12
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 21Go to Step 13
131. Disconnect the vacuum hose from the fuel
pressure regulator and inspect the hose for the
presence of fuel.
2. If fuel is presence in the vacuum hose, replace
the fuel pressure regulator.
Is the repair complete?–Go to Step 21Go to Step 14
141. Turn the ignition ON.
2. Slowly press the acceleration pedal.
Does the Throttle Position (TP) sensor display in-
crease steady and evenly from its minimum voltage
at closed throttle to its maximum voltage at Wide–
Open Throttle (WOT).–Go to Step 15Go to Step 19
151. Perform the Fuel System Diagnosis.
2. If the table isolate a problem, repair as needed.
Is the repair complete?–Go to Step 21Go to Step 16
161. Perform the Evaporative Emission (EVAP)
Control System Diagnosis.
2. If the table isolate a problem, repair as needed.
Is the repair complete?–Go to Step 21Go to Step 17
171. Perform the Fuel Injector Balance Test.
2. If the table isolate a problem, repair as needed.
Is the repair complete?–Go to Step 21Go to Step 18
181. Remove the Front Heated Oxygen Sensor
(HO2S1).
2. Visually/physically inspect the HO2S1 for sili-
cone contamination.
Note : this will be indicated by a powdery white de-
posit on the portion of the HO2S1 exposed to the ex-
haust stream.
1. If contamination is present on the HO2S1, find
the source and repair as needed.
Is the repair complete?–Go to Step 21Go to
”Diagnostic
Aids”
191. Check the TP sensor mounting screws.
2. If they are too loose or missing tighten or re-
place them as needed.
3. If the screws are OK, replace the TP sensor.
Is the repair complete?–Go to Step 21–