TEST ACTION APPLICABILITY
4 Disconnect the 1/2 O2 Sensor Connector.
Check connectors - Clean / repair as necessary.
Is any terminal corroded, damaged, pushed out or miswired?All
Ye s®Repair or replace as necessary.
Perform VERIFICATION TEST VER-5A3.
No®Go To 5
5 Turn Ignition On (Engine Off).
Disconnect the 1/2 O2 Sensor Connector.
Check connectors - Clean / repair as necessary.
With the DRB, actuate the ASD Relay.
Using a voltmeter, measure the ASD Relay Output Circuit at the O2 Sensor
Connector (harness side).
Is the voltage above 10.0 volts?All
Ye s®Go To 6
No®Repair the open ASD Relay Output Circuit.
Perform VERIFICATION TEST VER-5A3.
6 Disconnect the 1/2 O2 Sensor Connector.
Check connectors - Clean / repair as necessary.
Using an ohmmeter, measure the O2 Sensor Heater Element at the O2 Sensor
Connector (component side).
Is the resistance between 4 and 7 ohms?All
Ye s®Go To 7
No®Replace the 1/2 O2 Sensor.
Perform VERIFICATION TEST VER-5A3.
7 Disconnect the 1/2 O2 Sensor Connector.
Check connectors - Clean / repair as necessary.
Using an ohmmeter, measure from the Heater Ground Circuit to ground at the O2
Sensor Connector (harness side).
Is the resistance below 5.0 ohms?All
Ye s®Replace the 1/2 O2 Sensor.
Perform VERIFICATION TEST VER-5A3.
No®Repair the open 1/2 O2 Sensor Ground Circuit.
Perform VERIFICATION TEST VER-5A3.
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DRIVEABILITY
P-0141 1/2 O2S HEATER FAILURE ÐContinued
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Symptom:
P-0171±1/1 FUEL SYSTEM LEAN
When Monitored and Set Condition:
P-0171±1/1 FUEL SYSTEM LEAN
When Monitored: With the engine running in closed loop mode, the ambient, battery
temperature above Ð5 deg. C (20 deg. F) and altitude below 8000 ft.
Set Condition: If the PCM multiplies short term compensation by long term adaptive and
a certain percentage is exceeded for two trips, a freeze frame is stored, the MIL illuminates
and a trouble code is stored.
POSSIBLE CAUSES
FUEL PUMP MODULE DEFECTIVE
TPS VOLTAGE CHANGE NOT SMOOTH
TPS VOLTAGE <0.92V
FUEL INLET STRAINER PLUGGED
ECT SENSOR DEFECTIVE (OUT OF CALIBRATION)
MAP SENSOR DEFECTIVE (OUT OF CALIBRATION)
ENGINE MECHANICAL PROBLEM
FUEL FILTER/PRESSURE REGULATOR DEFECTIVE (HIGH)
FUEL FILTER/PRESSURE REGULATOR DEFECTIVE (LOW)
FUEL PUMP CAPACITY (VOLUME) OUT OF SPECS
TEST ACTION APPLICABILITY
1 Turn ignition on.
With the DRB, read the DTC's.
Is the Global Good Trip Counter displayed and equal to zero for P0171?All
Ye s®Go To 2
No®Go To 13
2 Ignition On, Engine Not Running
With the DRB, read the TPS voltage.
While monitoring the DRB, slowly open and close the Throttle.
Is the voltage change smooth?All
Ye s®Go To 3
No®Replace the Throttle Position Sensor.
Perform Powertrain Verification Test VER-5A.
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TEST ACTION APPLICABILITY
3 Ignition On, Engine Not Running.
With the DRB, read TPS Sensor voltage. Throttle must be against stop.
Is the voltage 0.92 or less with the Throttle closed?All
Ye s®Go To 4
No®Replace the Throttle Position Sensor.
Perform Powertrain Verification Test VER-5A.
4 Turn ignition On.
With the DRB in sensors, read the ªEngine Coolant Tmp Degº value.
Note: If engine coolant temperature is above 82ÉC (180ÉF), allow the engine
to cool until 62ÉC (150ÉF) is reached.
Start the Engine.
While monitoring the DRB, allow the engine to reach normal operating temperature
above 82ÉC (180ÉF).
Did the engine coolant temperature value reach 82ÉC (180ÉF) or above?All
Ye s®Go To 5
No®Replace the Engine Coolant Temperature Sensor.
Perform Powertrain Verification Test VER-5A.
5 Turn ignition On.
With the DRB in sensors, read the88Eng Coolant Tmp Deg'' value
Note: If engine coolant temperature is above 82ÉC (180ÉF), allow the engine
to cool until 62ÉC (150ÉF) is reached.
Start the Engine.
While monitoring the DRB, allow the engine to reach normal operating temperature
above 82ÉC (180ÉF).
Was the coolant temperature value increase a smooth transition?All
Ye s®Go To 6
No®Replace the Engine Coolant Temperature Sensor.
Perform Verificatino Test VER-5A.
6 Turn ignition off.
Connect a Vacuum Gauge to a Manifold Vacuum source.
Start the engine.
Allow the engine to idle.
Note: If engine will not idle, maintain a constant RPM above idle.
Using the DRB in Sensors, read the MAP Sensor vacuum value.
Is the DRB reading within 19of the Vacuum Gauge reading?All
Ye s®Go To 7
No®Replace the MAP Sensor.
Perform Powertrain Verification Test VER-5A.
76
DRIVEABILITY
P-0171±1/1 FUEL SYSTEM LEAN ÐContinued
ProCarManuals.com
Symptom
P0172 -1/1 FUEL SYSTEM RICH
When Monitored and Set Condition:
P0172 -1/1 FUEL SYSTEM RICH
When Monitored: With the engine in closed loop mode, the ambient/battery temperature
above þ5 deg. C (20 deg. F) and altitude below 8000 ft.
Set Condition: If the PCM multiplies short term compensation by long term adaptive and
the result is below a certain value for two trips, a freeze frame is stored, the MIL
illuminates and a trouble code is stored.
POSSIBLE CAUSES
FUEL PUMP MODULE DEFECTIVE
TPS VOLTAGE CHANGE NOT SMOOTH
TPS VOLTAGE <0.92V
FUEL INLET STRAINER PLUGGED
ECT SENSOR DEFECTIVE (OUT OF CALIBRATION)
MAP SENSOR DEFECTIVE (OUT OF CALIBRATION)
ENGINE MECHANICAL PROBLEM
FUEL FILTER/PRESSURE REGULATOR DEFECTIVE (HIGH)
FUEL FILTER/PRESSURE REGULATOR DEFECTIVE (LOW)
TEST ACTION APPLICABILITY
1 Turn ignition on.
With the DRB, read the DTC's.
Is the DTC Specific Good Trip Counter displayed and equal to zero?All
Ye s®Go To 2
No®Go To 14
2 Ignition On, Engine Not Running
With the DRB, read the TPS voltage.
While monitoring the DRB, slowly open and close the Throttle.
Is the voltage change smooth?All
Ye s®Go To 3
No®Replace the Throttle Position Sensor.
Perform Powertrain Verification Test VER-5A.
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TEST ACTION APPLICABILITY
3 Ignition On, Engine Not Running.
With the DRB, read TP Sensor voltage. Throttle must be against stop.
Is the voltage 0.92 or less with the Throttle closed?All
Ye s®Go To 4
No®Replace the Throttle Position Sensor.
Perform Powertrain Verification Test VER-5A.
4 Turn ignition on.
With the DRB in sensors, read the ªEng Coolant Tmp Degº value.
Note: If engine coolant temperature is above 82ÉC (180ÉF), allow the engine
to cool until 62ÉC (150ÉF) is reached.
Start the Engine.
While monitoring the DRB, allow the engine to reach normal operating temperature
above 82ÉC (180ÉF).
Did the engine coolant temperature value reach 180ÉF or above?All
Ye s®Go To 5
No®Replace the Engine Coolant Temperature Sensor.
Perform Powertrain Verification Test VER-5A.
5 Turn ignition On.
With the DRB in sensors, read the ªEng Coolant Tmp Deg'' value
Note: If engine coolant temperature is above 82ÉC (180ÉF), allow the engine
to cool until 62ÉC (150ÉF) is reached.
Start the Engine.
While monitoring the DRB, allow the engine to reach normal operating temperature
above 82ÉC (180ÉF).
Was the coolant temperature value increase a smooth transition?All
Ye s®Go To 6
No®Replace the Engine Coolant Temperature Sensor.
Perform Verification Test VER-5A.
6 Turn ignition off.
Connect a Vacuum Gauge to a Manifold Vacuum source.
Start the engine.
Allow the engine to idle.
Note: If engine will not idle, maintain a constant RPM above idle.
Using the DRB in Sensors, read the MAP Sensor vacuum value.
Is the DRB reading within 19of the Vacuum Gauge reading?All
Ye s®Go To 7
No®Replace the MAP Sensor.
Perform Powertrain Verification Test VER-5A.
7Note: Engine must be at operating temp and in closed loop to perform this
test.
Start engine and run until operating temp and closed loop mode is reached.
With the DRB under System Tests, go to ªPurge Vapors Test''. Observe the Short
Term Adaptive value and press 3 to flow.
Note: Short Term Adaptive should change.
Did the Short Term Adaptive value change?All
Ye s®Go To 8
No®Refer to symptom *CHECKING EVAPORATIVE EMISSION
SYSTEM in the DRIVEABILITY category.
80
P0172 -1/1 FUEL SYSTEM RICH ÐContinued
ProCarManuals.com
Symptom List:
P-0300 MULTIPLE CYLINDER MIS-FIRE
P-0301 CYLINDER #1 MIS-FIRE
P-0302 CYLINDER #2 MIS-FIRE
P-0303 CYLINDER #3 MIS-FIRE
P-0304 CYLINDER #4 MIS-FIRE
Test Note: All symptoms listed above are diagnosed using the same tests.
The title for the tests will be P-0300 MULTIPLE CYLINDER
MIS-FIRE.
When Monitored and Set Condition:
P-0300 MULTIPLE CYLINDER MIS-FIRE
When Monitored: With the engine running, after successfully performing Crank Sensor
learn.
Set Condition: When more than a 2% misfire rate is measured during two trips, or with
a 10% to 30% misfire rate during one trip.
P-0301 CYLINDER #1 MIS-FIRE
When Monitored: With the engine running, after successfully performing Crank Sensor
learn.
Set Condition: When more than a 2% misfire rate is measured during two trips, or with
a 10% to 30% misfire rate during one trip.
P-0302 CYLINDER #2 MIS-FIRE
When Monitored: With the engine running, after successfully performing Crank Sensor
learn.
Set Condition: When more than a 2% misfire rate is measured during two trips, or with
a 10% to 30% misfire rate during one trip.
P-0303 CYLINDER #3 MIS-FIRE
When Monitored: With the engine running, after successfully performing Crank Sensor
learn.
Set Condition: When more than a 2% misfire rate is measured during two trips, or with
a 10% to 30% misfire rate during one trip.
P-0304 CYLINDER #4 MIS-FIRE
When Monitored: With the engine running, after successfully performing Crank Sensor
learn.
Set Condition: When more than a 2% misfire rate is measured during two trips, or with
a 10% to 30% misfire rate during one trip.
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TEST ACTION APPLICABILITY
5 With an appropriate container, obtain a fuel sample from the vehicle.
Is the fuel free from contamination?All
Ye s®Go To 6
No®Replace contaminated fuel and clean system.
Perform VERIFICATION TEST VER-5A2.
6 Perform Fuel Pressure Leak Down Test per service instructions.
Did the Fuel Pressure Leak Down Test pass?All
Ye s®Go To 7
No®Relieve fuel pressure and repair as necessary.
Perform VERIFICATION TEST VER-5A2.
7 Perform Fuel Pump Amperage Test per service instructions.
Did the Fuel Pump Amperage Test pass?All
Ye s®Go To 8
No®Relieve fuel pressure and repair as necessary.
Perform VERIFICATION TEST VER-5A2.
8 Perform Fuel Pump Capacity Test per service instructions.
Did the Fuel Pump Capacity Test pass?All
Ye s®Go To 9
No®Relieve fuel pressure and repair as necessary.
Perform VERIFICATION TEST VER-5A2.
9 Perform Fuel Pump Pressure Test per service instructions.
Did the Fuel Pump Pressure Test pass?All
Ye s®Go To 10
No®Relieve fuel pressure and repair as necessary.
Perform VERIFICATION TEST VER-5A2.
10 With the DRB, read the FREEZE FRAME DATA.
Use the freeze frame data and attempt to determine the cause.
In the FREEZE FRAME, is the LOAD VALUE over 50% and the temp normal
operating temp normal?All
Ye s®Go To 12
No®Go To 11
11 With the DRB, read the FREEZE FRAME window.
Use the freeze frame data and attempt to determine the cause.
In the FREEZE FRAME, is the ENGINE RPM over 3000 and the operating temp
normal?All
Ye s®Lab scope cam and crank sensor, check valve timing, running
vacuum test.
Perform VERIFICATION TEST VER-5A2.
No®Go To 14
102
DRIVEABILITY
P-0300 MULTIPLE CYLINDER MIS-FIRE ÐContinued
ProCarManuals.com
Symptom List:
P-0305 CYLINDER #5 MIS-FIRE
P-0306 CYLINDER #6 MIS-FIRE
Test Note: All symptoms listed above are diagnosed using the same tests.
The title for the tests will be P-0305 CYLINDER #5 MIS-FIRE.
When Monitored and Set Condition:
P-0305 CYLINDER #5 MIS-FIRE
When Monitored: With the engine running, after successfully performing Crank Sensor
learn.
Set Condition: When more than a 2% misfire rate is measured during two trips, or with
a 10% to 30% misfire rate during one trip.
P-0306 CYLINDER #6 MIS-FIRE
When Monitored: With the engine running, after successfully performing Crank Sensor
learn.
Set Condition: When more than a 2% misfire rate is measured during two trips, or with
a 10% to 30% misfire rate during one trip.
POSSIBLE CAUSES
OTHER POSSIBLE CAUSES FOR MIS-FIRE
CAM, CRANK, VALVE TIMING, OR VACUUM PROBLEM
ELECTRONIC IGNITION COIL OUTPUT LOW
ENGINE MECHANICAL PROBLEM
SECONDARY IGNITION PATTERN IRREGULAR
FUEL CONTAMINATION
FUEL PRESSURE LEAK DOWN OUT OF SPECIFICATION
FUEL PUMP AMPERAGE OUT OF SPECIFICATION
FUEL PUMP CAPACITY OUT OF SPECIFICATION
FUEL PUMP PRESSURE OUT OF SPECIFICATION
MIS-FIRE DOES NOT REOCCUR
TEST ACTION APPLICABILITY
1 With the DRB, read the DTCs.
Is the MIS-FIRE GOOD TRIP counter displayed and equal to zero?ENGINE - 3.0L V6
and/or ENGINE -
3.3L V6 and/or EN-
GINE - 3.8L V6
and/or ENGINE -
3.3L V6 FFV Ye s®Go To 2
No®Go To 3
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