Opel Frontera UBS. Service manual — part 2295
6E–216
6VE1 3.5 ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P0172 Fuel Trim System Rich Bank 1
D06R200010
Circuit 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 powertrain control module (PCM) monitors the Bank 1
heated oxygen sensors (HO2S) 1 and Bank 2 HO2S 1
signals and adjusts fuel delivery based upon the HO2S
signal voltages. A change made to fuel delivery will be
indicated by the long and short term fuel trim values which
can be monitored with a Tech 2. Ideal fuel trim values are
around 0%; if the HO2S signals are indicating a lean
condition the PCM will add fuel, resulting in fuel trim
values above 0%. If a rich condition is detected, the fuel
trim values will be below 0%, indicating that the PCM is
reducing the amount of fuel delivered. If an excessively
rich condition is detected on Bank 1, the PCM will set DTC
P0172.
The PCM’s maximum authority to control long term fuel
trim allows a range between –15% (automatic
transmission) or –12 (manual transmission) and +20%.
The PCM’s maximum authority to control short term fuel
trim allows a range between –11% and +20%. The PCM
monitors fuel trim under various engine speed/load fuel
trim cells before determining the status of the fuel trim
diagnostic.
Conditions for Setting the DTC
D
None of the following was set: EGR DTCs, HO2S
DTCs, (response, transition, open, low volts, no
activity), MAF DTCs, TPS DTCs, MAP DTCs, IAT
DTCs, canister purge DTCs, EVAP DTCs, injector
circuit DTCs, or misfire DTCs.
D
Engine coolant temperature is between 6
°
C (42.8
°
F)
and 105
°
C (221
°
F).
D
Intake air temperature is between –40
°
C (–40
°
F) and
120
°
C (248
°
F).
D
Manifold absolute pressure is between 24 kPa and 99
kPa.
D
Throttle angle is steady below 95%.
D
Vehicle speed is below 136 km/h (85 mph).
D
Engine speed is between 400 and 6,000 RPM.
D
Barometric pressure is greater than 72.5 kPa.
D
Mass air flow is between 2 g/second and 200 g/second.
D
Ignition voltage is above 9.5 volts.
D
Fuel system is in “closed loop”.
D
Canister purge duty cycle is greater than 0%, if “ON”.
Action Taken When the DTC Sets
D
The PCM will illuminate the malfunction indicator lamp
(MIL) after the second consecutive trip in which the
fault is detected.
D
The PCM will store conditions which were present
when the DTC was set as Freeze Frame and in the
Failure Records data.
Conditions for Clearing the MIL/DTC
D
The PCM will turn the MIL “OFF” on the third
consecutive trip cycle during which the diagnostic has
been run and the fault condition is no longer present.
6E–217
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
D
A history DTC P0172 will clear after 40 consecutive
warm-up cycles have occurred without a fault.
D
DTC P0172 can be cleared by using the Tech 2 “Clear
Info” function or by disconnecting the PCM battery
feed.
Diagnostic Aids
Check for the following conditions:
D
Poor connection at PCM – Inspect harness connectors
for backed-out terminals, improper mating, broken
locks, improperly formed or damaged terminals, and
poor terminal-to-wire connection.
D
Damaged harness – Inspect the wiring harness for
damage. If the harness appears to be OK, observe the
Bank 1 HO2S 1 display on the Tech 2 while moving
connectors and wiring harnesses related to the engine
harness. A change in the display will indicate the
location of the fault.
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.
Test Description
Number(s) below refer to the step number(s) on the
Diagnostic Chart.
2. DTCs other than P0172 and P0175 may indicate a
condition present which may cause a lean condition.
If this is the case, repairing the condition which
caused the other DTC will most likely correct the
DTC P0172/P0175.
4. If the DTC P0172 test passes while the Failure
Records conditions are being duplicated, the rich
condition is intermittent. Refer to
Diagnostic Aids or
Symptoms for additional information on diagnosing
intermittent problems.
DTC P0172 – Fuel Trim System Rich Bank 1
Step
Action
Value(s)
Yes
No
1
Was the “On-Board Diagnostic (OBD) System Check”
performed?
—
Go to
Step 2
Go to
OBD
System
Check
2
Are any DTCs set other than P0172 and P0175?
—
Go to the
applicable
DTC charts
and repair the
other DTCs
before
proceeding
with this chart
Go to
Step 3
3
1. Start the engine and operate the vehicle in “closed
loop”.
2. Observe “B1 Long Term Fuel Trim” display on the
Tech 2.
Is the displayed value more negative than the specified
value?
L.T. Fuel
Trim: –15%
(auto. trans.)
OR –12%
(man. trans.)
Go to
Step 5
Go to
Step 4
4
1. Review and record the Tech 2 Failure Records data.
2. Clear the DTC P0172/P0175 and operate the
vehicle to duplicate the Failure Records conditions.
3. Monitor the Tech 2 “DTC” info for DTC P0172 while
operating the vehicle to duplicate the Failure
Records conditions.
4. Continue operating the vehicle until the DTC P0172
test runs and note test result.
Does the Tech 2 indicate DTC P0172 failed this
ignition?
—
Go to
Step 5
The rich
condition is
not present.
If a
driveability
symptom still
exists, refer
to
Symptoms.
5
Is DTC P0175 also set?
—
Go to
Step 6
Go to
Step 15
6
Visually and physically inspect the air filter element and
replace it if necessary.
Did the air filter require replacement?
—
Verify repair
Go to
Step 7
7
Visually and physically inspect the air intake duct for
collapse or restriction and repair if necessary.
Did your inspection reveal a condition requiring repair?
—
Verify repair
Go to
Step 8
6E–218
6VE1 3.5 ENGINE DRIVEABILITY AND EMISSIONS
DTC P0172 – Fuel Trim System Rich Bank 1
(Cont'd)
Step
No
Yes
Value(s)
Action
8
Inspect the MAF sensor inlet screen for damage or for
the presence of foreign objects which may partially
block air flow through the screen and correct any
problem found.
Did your inspection of the MAF sensor reveal a
condition requiring repair or replacement?
—
Verify repair
Go to
Step 9
9
Start the engine and note the idle quality.
Is a low or unsteady idle being experienced?
—
Go to
Step 10
Go to
Step 11
10
1. Ignition “OFF”.
2. Physically inspect the throttle body bore and throttle
plate for coking and foreign objects.
3. If a problem was found, repair as necessary.
Did your inspection reveal a condition requiring repair?
—
Verify repair
Go to
Step 11
11
1. Disconnect the vacuum hose from the fuel pressure
regulator and inspect the hose for the presence of
fuel.
2. If fuel is present in the vacuum hose, replace the
fuel pressure regulator (refer to
Fuel Metering
System).
Did the fuel pressure regulator require replacement?
—
Verify repair
Go to
Step 12
12
Ignition “ON”, engine “OFF”, monitor the TP1 Angle
display on the Tech 2 while slowly depressing the
accelerator pedal.
Does the TP Angle display increase steadily and
evenly from minimum value at closed throttle to
maximum value at wide-open throttle?
Minimum 8%
Maximum
92%
Go to
Step 13
Go to
Step 21
13
1. Disconnect the MAF sensor electrical connector.
2. Operate the vehicle in “closed loop” while
monitoring the “BANK 1 L.T. FUEL TRIM” and
“BANK 1 S. T. FUEL TRIM” display on the Tech 2.
Did both values change to near the specified value?
0%
Go to
Step 22
Go to
Step 14
14
1. Perform “Fuel System Pressure Test”.
2. If Fuel System Pressure Test isolates a problem,
repair as necessary (refer to
Engine Fuel or Fuel
Metering System).
Did the Fuel System Pressure Test isolate a problem
requiring repair?
—
Verify repair
Go to
Step 15
15
1. Ignition “ON”, engine “OFF”.
2. Connect a test light between the harness connector
terminals of canister purge solenoid.
Is the test light on?
—
Go to
Step 16
Go to
Step 19
16
Check for short to ground in the wire (YEL/RED)
between the canister purge solenoid and PCM terminal
S-48.
Was there a short to ground?
—
Go to
Step 17
Go to
Step 18
17
Repair the short to ground.
Is the action complete?
—
Verify repair
—
6E–219
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
DTC P0172 – Fuel Trim System Rich Bank 1
(Cont'd)
Step
No
Yes
Value(s)
Action
18
Replace the PCM.
IMPORTANT: The replacement PCM must be
programmed. Refer to
On-Vehicle Service in
Powertrain Control Module and Sensors for
procedures.
And also refer to the latest Service Bulletin.
Check to see if the Latest software is released or not.
And then Down Load the LATEST PROGRAMMED
SOFTWARE to the replacement PCM.
Is the action complete?
—
Verify repair
—
19
1. Perform the “Injector Balance Test”.
2. If Injector Balance Test isolates a problem, repair as
necessary (refer to
Fuel Metering System).
Did the Injector Balance Test isolate a problem
requiring repair?
—
Verify repair
Go to
Step 20
20
1. Remove and visually/physically inspect the Bank 1
HO2S 1 for silicon contamination. This will be
indicated by a powdery deposit on the portion of the
HO2S that is exposed to the exhaust stream.
2. If contamination is evident on the Bank 1 HO2S 1,
replace the contaminated sensors.
Did the sensor require replacement?
—
Verify repair
Check the
Procedure
Refer to
Diagnostic
Aids
21
1. Check the TP sensor mounting screws and tighten
or replace them as necessary if they are loose or
missing.
2. If the screws are OK, replace the TP sensor.
Is the action complete?
—
Verify repair
—
22
Replace the MAF sensor.
Is the action complete?
—
Verify repair
—
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