Symptom:
P-0141 1/2 O2S HEATER FAILURE
When Monitored and Set Condition:
P-0141 1/2 O2S HEATER FAILURE
When Monitored: With the ignition key off, after the engine cools down.
Set Condition: No sensor output signal is received when the PCM powers up the sensor
heater.
POSSIBLE CAUSES
1/2 O2 SENSOR CONNECTOR DAMAGED
1/2 O2 SENSOR GND CIRCUIT OPEN
ASD RELAY OUTPUT CIRCUIT OPEN
1/2 O2 SENSOR FAILURE
1/2 O2 SENSOR HEATER ELEMENT FAILURE
1/2 O2S HEATER FAILURE DOES NOT REOCCUR
TEST ACTION APPLICABILITY
1 With the DRB, read the DTCs.
Is the GLOBAL GOOD TRIP counter displayed and equal to zero?All
Ye s®Go To 2
No®Go To 3
2 Turn Ignition On (Engine Off), wait three minutes.
With the DRB, monitor the O2 Sensor voltage for a few minutes until the voltage
stabilizes between .4 and .6 volts.
With the DRB, actuate the O2 Heater test.
Monitor O2 voltage for up to two minutes.
Is the O2 Sensor voltage still between .4 and .6 volts?All
Ye s®Go To 3
No®Go To 4
3 At this time the 1/2 O2S HEATER FAILURE does not exist or is an intermittent
problem.
With the DRB, read the FREEZE FRAME DATA.
With this screen, attempt to duplicate the condition that has set this fault.
While using FREEZE FRAME DATA pay particular attention to the fault setting
conditions, such as speed, temp, load, and map vacuum.
Does the 1/2 O2S HEATER FAILURE reoccur?All
Ye s®Go To 4
No®1/2 O2S Heater failure no longer exists.
Perform VERIFICATION TEST VER-5A3.
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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.
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DRIVEABILITY
P-0171±1/1 FUEL SYSTEM LEAN ÐContinued
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TEST ACTION APPLICABILITY
7 Turn ignition off.
Warning: The fuel system is under a constant pressure (even with the engine
off). Before testing or servicing any fuel system hose, fitting or line, the fuel
system pressure must be released.
Remove the pressure test port cap at the fuel rail test port. Connect a fuel pressure
gauge to the test port pressure fitting on the fuel rail.
Ignition on. With the DRB, actuate the ASD Fuel System test and observe the fuel
pressure gauge.
Note: Fuel pressure specification is 49.2 psi +/- 5 psi
Choose a conclusion that best matches your fuel pressure reading.All
Below Specification
Go To 8
Within Specification
Go To 11
Above Specification
Replace the fuel filter pressure regulator.
Caution: Stop ALL Actuations.
8 Turn ignition off.
Warning: The fuel system is under a constant pressure (even with the engine
off). Before testing or servicing any fuel system hose, fitting or line, the fuel
system pressure must be released.
Raise vehicle on hoist,and disconnect the fuel pressure line at the fuel pump module.
Install speial 5/169fuel line adapter tool #6539 between disconnected fuel line and
the fuel pump module.
Attach a fuel pressure test gauge to the88T'' fitting on tool #6539.
Ignition on. With the DRB, actuate the ASD Fuel System test and observe the fuel
pressure gauge.
Note: Fuel pressure specification is 49.2 psi +/- 5 psi.
Is the fuel pressure within specification now?ALL
Ye s®Repair the restriction in the chassis fuel supply line between the
fuel tank and fuel rail.
No®Go to 9
Caution: Stop ALL Actuations.
9Warning: The fuel system is under a constant pressure (even with the engine
off). Before testing or servicing any fuel system hose, fitting or line, the fuel
system pressure must be released.
Remove the Fuel Pump Module and inspect the Fuel Inlet Strainer.
Is the Fuel Inlet Strainer plugged?All
Ye s®Replace the Fuel Inlet Strainer.
No®Go To 10
10 If there are no potential causes remaining, the Fuel Pump Module is assumed to be
defective.
View repair options.All
Repair
Replace the Fuel Pump Module
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DRIVEABILITY
P-0171±1/1 FUEL SYSTEM LEAN ÐContinued
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TEST ACTION APPLICABILITY
11 Check for any of the following conditions/mechanical problems.
ENGINE VACUUM Ð must be at least 13 inches in neutral
ENGINE VALVE TIMING Ð must be within specifications
ENGINE COMPRESSION Ð must be within specifications
ENGINE EXHAUST SYSTEM Ð must be free of any restrictions or leaks
ENGINE PVC SYSTEM Ð must flow freely
TORQUE CONVERTER STALL SPEED Ð must be within specifications
POWER BRAKE BOOSTER Ð no internal vacuum leaks
FUEL- must be free of contamination
FUEL INJECTOR Ð plugged or restricted injector; control wire not connected to
correct injector.
Are there any engine mechanical problems?All
Ye s®Repair as necessary.
Perform FUEL SYSTEM/MISFIRE MONITOR VERIFICATION
TEST
No®Go To 12
12 Turn ignition off.
Warning: The fuel system is under constant pressure (even with the engine
off). Before testing or servicing any fuel system hose, fitting or line, the fuel
system pressure must be released.
Disconnect the fuel supply line at the fuel rail.
Connect fuel line adapter #6539(5/169) or #6631 (3/89) to the disconnected fuel supply
line. Insert the other end of the adapter into a graduated container.
Caution: Do not operate the fuel pump for more than 7 seconds in the next
step. Fuel pump module reservoir may run empty and damage to the fuel
pump may result.
Specification: A good fuel pump will deliver at least 1/4 liter of fuel in 7
seconds.
With the DRB, actuate the ASD Fuel System test for 7 seconds.
Is the fuel pump capacity within specification?All
Ye s®Test Complete.
No®Check for a kinked/damaged fuel supply line between the fuel
tank and fuel rail. If OK, replace the fuel filter/pressure regulator.
Caution: Stop ALL Actuations.
13 The conditions required to set the DTC are no longer present.
With the DRB read and record the freeze frame data and the ªFuel System Similar
Conditions Windowº data.
Utilize the data and try to duplicate the operating conditions at which the DTC was
set. Pay particular attention to the ECT and RPM for added diagnostics.
Note: Refer to any TSB's that may apply to the symptom.
Test Complete
Repair
Test Complete.
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DRIVEABILITY
P-0171±1/1 FUEL SYSTEM LEAN ÐContinued
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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.
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P0172 -1/1 FUEL SYSTEM RICH ÐContinued
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