6E–96
ENGINE DRIVEABILITY AND EMISSIONS
Knock Sensor (KS) System Check
(Engine Knock, Poor Performance, or Poor Economy)
StepActionVa l u e ( s )Ye sNo
1Is DTC P0325 or P0327 set?
—
Go to DTC
P0325 or
DTC P0327
Go to Step 2
2Run the engine at 1500 RPM.
Is there an internal engine knock?
—Go to Step 3Go to Step 4
3Repair the mechanical problem.
Is the action complete?
—Verify repair—
41. Install Tech 2.
2. Turn the ignition “ON.”
3. Cycle through the list until “Knock Retard” is
displayed.
Is knock retard at the specified value?
0Go to Step 6Go to Step 7
5Replace the PCM.
IMPORTANT:The replacement PCM must be
programmed. Refer to
UBS 98model year Immobilizer
Workshop Manual.
Is the action complete?—Verify repair—
61. Start the engine.
2. Monitor the knock retard display on Tech 2 while
changing the throttle setting to place different loads
on the engine.
Is knock retard at the specified value? (Turn the ignition
“OFF.”)
0Go to Step 9Go to Step 7
71. At the rear of the engine, behind the rear fuel
injector on the lift side, disconnect the 2-wire knock
sensor harness connector.
2. Attach the positive lead of DVM to B+.
3. On the m ain harness side of the connector, use th e
negative lead of the DVM to probe the connector pin
that is connected to the black wire.
Dose the DVM indicate the specified value?
(Reconnect the knock sensor harness.)
B+Go to Step 9Go to Step 8
8Repair the open black wire ground for the shield which
prevents stray electromagnetic pulses from affecting
the knock signal.
Is the action complete?
—Verify repair—
91. Reconnect the wire harness.
2. Set a DVM to AC voltage.
3. With the DVM, backprobe the PCM connector at
A2.
4. Tap the engine lift brackprobe with a socket
extension.
Did the DVM show an increase in AC voltage while
tapping on the lift bracket?
—System OKGo to Step 10
10Replace the knock sensor.
Is the action complete?
—Verify repair—
6E–111 ENGINE DRIVEABILITY AND EMISSIONS
DTC P0103 – MAF Sensor Circuit High Frequency
StepActionVa l u e ( s )Ye sNo
1Was the “On-Board Diagnostic (OBD) System Check”
performed?
—Go to Step 2
Go to OBD
System
Check
21. Ignition “ON,” engine “OFF.”
2. Review and record Tech 2 Failure Records data.
3. Operate the vehicle within Failure Records
conditions as noted.
4. Using a Tech 2, monitor “DTC” info for DTC P0103.
Does the Tech 2 indicate DTC P0103 failed this
ignition?
—Go to Step 3
Refer to
Diagnostic
Aids
31. Start the engine.
2. With the engine idling, monitor “MAF Frequency”
display on the Tech 2.
Is “MAF Frequency” above the specified value?
219 g/SecGo to Step 4Go to Step 7
41. Ignition “OFF.”
2. Disconnect the MAF sensor connector.
3. Ignition “ON,” engine idling.
4. Using a Tech 2, monitor “MAF Frequency.”
Does the Tech 2 indicate a “MAF Frequency” at the
specified value?
0.0 g/SecGo to Step 5Go to Step 6
5Replace the MAF sensor.
Is the action complete?
—Verify repairGo to Step 8
61. Check the MAF harness for incorrect routing near
high voltage components (solenoids, relays,
motors).
2. If incorrect routing is found, correct the harness
routing.
Was a problem found?
—Verify repairGo to Step 7
71. With the engine idling, monitor “MAF Frequency”
display on the Tech 2.
2. Quickly snap open throttle to wide open throttle
while under a road load and record value.
Does the Tech 2 indicate “MAF Frequency” above the
specified value?
219 g/SecGo to Step 5Go to Step 8
8Replace the PCM.
IMPORTANT:The replacement PCM must be
programmed. Refer to
UBS 98model year Immobilizer
Workshop Manual.
Is the action complete?—Verify repair—
6E–120
ENGINE DRIVEABILITY AND EMISSIONS
DTC P0112–IAT Sensor Circuit Low Voltage
StepActionVa l u e ( s )Ye sNo
1Was the “On-Board Diagnostic (OBD) System Check”
performed?
—Go to Step 2
Go to OBD
System
Check
21. Ignition “ON,” engine “OFF.”
2. Using a Tech 2, monitor the intake air temperature
(IAT).
Is the intake air temperature greater than the specified
value?
148C
(283
F)Go to Step 4Go to Step 3
31. Ignition “ON,” engine “OFF.” Review and record
Tech 2 Failure Records data.
2. Operate the vehicle within Failure Records
conditions as noted.
3. Using a Tech 2, monitor the “Specific DTC” info for
DTC P0112.
Does the Tech 2 indicate DTC P0112 failed this
ignition?
—
Refer to Te s t
Description
Refer to
Diagnostic
Aids
41. Ignition “OFF.”
2. Disconnect the IAT sensor electrical connector.
3. Ignition “ON.”
4. Observe the intake air temperature on the Tech 2.
Is the intake air temperature below the specified value?
–38C
(–36
F)Go to Step 6Go to Step 5
51. Ignition “OFF.”
2. Disconnect the PCM electrical connectors.
3. Check the IAT sensor signal circuit for a short to
ground.
Is the IAT sensor signal circuit shorted to ground?
—Verify repairGo to Step 7
6Replace the IAT sensor.
Is the action complete?
—Verify repair—
7Replace the PCM.
IMPORTANT:The replacement PCM must be
programmed. Refer to
UBS 98model year Immobilizer
Workshop Manual.
Is the action complete?—Verify repair—
6E–126
ENGINE DRIVEABILITY AND EMISSIONS
DTC P0117 – ECT Sensor Low Voltage
StepActionVa l u e ( s )Ye sNo
1Was the “On-Board Diagnostic (OBD) System Check”
performed?
—Go to Step 2
Go to OBD
System
Check
21. Ignition “ON,” engine “OFF.”
2. Observe the “Eng Cool Temp” display on the Tech 2.
Is the “Eng Cool Temp” below the specified value?
139C
(282
F)Go to Step 4Go to Step 3
31. Ignition “ON,” engine “OFF.”
2. Review and record Tech 2 Failure Records data.
3. Operate the vehicle within Failure Records
conditions as noted.
4. Using a Tech 2, monitor “Specific DTC” info for DTC
P0117.
Does the Tech 2 indicate DTC P0117 failed this
ignition?
—Go to Step 4
Refer to
Diagnostic
Aids
41. Disconnect the ECT sensor electrical connector.
2. Observe the “Eng Cool Temp” display on the Tech 2.
Is the “Eng Cool Temp” at the specified value?
–39C
(–38
F)Go to Step 6Go to Step 5
51. Ignition “OFF.”
2. Disconnect the PCM and check the ECT signal
circuit for a short to ground or a short to the sensor
ground circuit.
3. If the ECT signal circuit is shorted. repair it as
necessary.
Was the ECT signal circuit shorted to ground?
—Verify repairGo to Step 7
6Replace the ECT sensor.
Is the action complete?
—Verify repair—
7Replace the PCM.
IMPORTANT:The replacement PCM must be
programmed. Refer to
UBS 98model year Immobilizer
Workshop Manual.
Is the action complete?—Verify repair—
6E–141 ENGINE DRIVEABILITY AND EMISSIONS
DTC P0131 –HO2S Circuit Low Voltage Bank 1 Sensor 1
StepNo Ye s Va l u e ( s ) Action
81. Ignition “OFF.”
2. Reconnect the PCM, leave the sensor
disconnected.
3. Ignition “ON.”
Does the Tech 2 indicate Bank 1 HO2S 1 voltage
between the specified values?
425-475 mV
Refer to
Diagnostic
Aids
Go to Step 9
9Replace the PCM.
IMPORTANT:The replacement PCM must be
programmed. Refer to
UBS 98model year Immobilizer
Workshop Manual.
Is the action complete?—Verify repair—
6E–142
ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P0132 HO2S Circuit High Voltage Bank 1
Sensor 1
060RW236
Circuit Description
The powertrain control module (PCM) supplies a bias
voltage of about 450 mV between the heated oxygen
sensor (HO2S) signal and low circuits. When measured
with a 10 megaohm digital voltmeter, this may display as
low as 320 mV. The oxygen sensor varies the voltage
within a range of about 1000 mV when exhaust is rich,
down through about 10 mV when exhaust is lean. The
PCM constantly monitors the HO2S signal during “closed
loop” operation and compensates for a rich or lean
condition by decreasing or increasing injector pulse width
as necessary. If the Bank 1 HO2S 1 voltage remains
excessively high for an extended period of time, DTC
P0132 will be set.
Conditions for Setting the DTC
No related DTCs.
Engine coolant temperature is above 60C (140F)
“Closed loop” commanded air/fuel ratio is between
14.5 and 14.8.
Throttle angle is between 3% and 19%.
Bank 1 HO2S 1 signal voltage remains above 952 mV
during normal “closed loop” operation for a total of 77
seconds over a 90-second period.
OR
Bank 1 HO2S 1 signal voltage remains above 500 mV
during “deceleration fuel cutoff mode” operation for 3
seconds.
Action Taken When the DTC Sets
The PCM will illuminate the malfunction indicator lamp
(MIL) the first time the fault is detected.
The PCM will store conditions which were present
when the DTC was set as Freeze Frame and in the
Failure Records data.
“Open loop” fuel control will be in effect.
Conditions for Clearing the MIL/DTC
DTC P0132 can be cleared by using the Tech 2 “Clear
Info” function or by disconnecting the PCM battery
feed.
Diagnostic Aids
Check the following items:
Fuel pressure – The system will go rich if pressure is
too high. The PCM can compensate for some
increase. However, if fuel pressure is too high, a DTC
P0132 may be set. Refer to
Fuel System Diagnosis.
Perform “Injector Balance Test” – Refer to Fuel System
Diagnosis.
MAF sensor –The system can go rich if MAF sensor
signal indicates an engine airflow measurement that is
not correct. Disconnect the MAF sensor to see it the
rich condition is corrected. If so, replace the MAF
sensor.
Check for a leak in the fuel pressure regulator
diaphragm by checking the vacuum line to the
regulator for the presence of fuel. There should be no
fuel in the vacuum line.
6E–143 ENGINE DRIVEABILITY AND EMISSIONS
An intermittent TP sensor output will cause the system
to go rich due to a false indication of the engine
accelerating.
Shorted Heated Oxygen Sensor (HO2S) –If the HO2S
is internally shorted, the HO2S voltage displayed on
the Tech 2 will be over 1 volt. Try disconnecting the
affected HO2S with the key “ON,” engine “OFF.” If the
displayed HO2S voltage changes from over 1000 mV
to around 450 mV, replace the HO2S. Silicon
contamination of the HO2S can also cause a high
HO2S voltage to be indicated. This condition is
indicated by a powdery white deposit on the portion of
the HO2S exposed to the exhaust stream. If
contamination is noticed, replace the affected HO2S.
Open HO2S Signal Circuit or Faulty HO2S–A poor
connection or open in the HO2S signal circuit can
cause the DTC to set during deceleration fuel mode.
A n H O 2 S w h i c h i s f a u l t y a n d n o t a l l o w i n g a f u l l v o l t a g e
swing between the rich and lean thresholds can also
cause this condition. Operate the vehicle by
monitoring the HO2S voltage with a Tech 2. If theHO2S voltage is limited within a range between 300
mV to 600 mV, check the HO2S signal circuit wiring
and associated terminal conditions.
If none of the above conditions are present, replace the
affected HO2S.
Test Description
Number(s) below refer to the step number(s) on the
Diagnostic Chart.
3. DTC P0132 failing during “deceleration fuel cutoff
mode” operation may indicate a condition described
in the “Diagnostic Aids” above. If the DTC P0132
test passes while the Failure Records conditions are
being duplicated, an intermittent condition is
indicated.
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.
DTC P0132 – HO2S Circuit High Voltage Bank 1 Sensor 1
StepActionVa l u e ( s )Ye sNo
1Was the “On-Board Diagnostic (OBD) System Check”
performed?
—Go to Step 2
Go to OBD
System
Check
21. Install the Tech 2.
2. Run the engine at operating temperature.
3. Operate the vehicle within parameters specified
under “Conditions for Setting the DTC” included in
Diagnostic Support.
4. Using a Tech 2, monitor Bank 1 HO2S 1 voltage.
Does the Bank 1 HO2S 1 voltage remain above the
specified value?
952 mV (500
mV in
deceleration
fuel cutoff
mode)
Go to Step 4Go to Step 3
31. Ignition “ON,” review and record Tech 2 Failure
Records data.
2. Operate the vehicle within Failure Records
conditions as noted.
3. Using a Tech 2, monitor “Specific DTC” info for DTC
P0132 until the DTC P0132 test runs.
4. Note the test result.
Does the Tech 2 indicate DTC P0132 failed this
ignition?
—Go to Step 4
Refer to
Diagnostic
Aids
41. Ignition “OFF.”
2. Disconnect Bank 1 HO2S 1.
3. Ignition “ON.”
4. At HO2S Bank 1 Sensor 1 connector (PCM side)
use a DVM to measure voltages at the high and low
signal terminals.
Are the voltages in the specified range?
3-4 VGo to Step 5Go to Step 6
5Repair short to voltage in signal circuit.
Is the action complete?
—Verify repair—
6E–150
ENGINE DRIVEABILITY AND EMISSIONS
DTC P0151 – HO2S Circuit Low Voltage Bank 2 Sensor 1
StepNo Ye s Va l u e ( s ) Action
81. Ignition “OFF.”
2. Reconnect the PCM, leave HO2S 2 disconnected.
3. Ignition “ON.”
Does Tech 2 indicate Bank 2 HO2S 1 voltage near the
specified value?
425-475 mV
Refer to
Diagnostic
Aids
Go to Step 9
9Replace the PCM.
IMPORTANT:The replacement PCM must be
programmed. Refer to
UBS 98model year Immobilizer
Workshop Manual.
Is the action complete?—Verify repair—