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Opel Frontera UE. Manual - part 942

6E2–154

6VD1 3.2L ENGINE DRIVEABILITY AND EMISSIONS

DTC P0171 –Fuel Trim System Lean Bank 1

(Cont'd)

Step

Yes

Value(s)

Action

Check the fuel for excessive water, alcohol, or other
contaminants (see

Diagnosis in Engine Fuel for the

procedure) and correct the contaminated fuel condition
if present (see

Engine Fuel).

Was the fuel contaminated?

—

Verify repair

Go to

Step 12

1. Visually and physically inspect the PCM injector

grounds, power grounds and sensor grounds to
ensure that they are clean, tight, and in their proper
locations.

2. If a faulty ground condition is present, correct it as

necessary.

Did your inspection reveal a condition requiring repair?

—

Verify repair

Go to

Step 13

1. Disconnect the MAF sensor electrical connector.
2. Operate the vehicle in “closed loop” while

monitoring the “B1 Long Term Fuel Trim” displayed
on the Tech 2.

Does “BANK 1 S.T. FUEL TRIM” value decrease to
near the specified value?

Go to

Step 19

Go to

Step 14

Perform the procedure in the “Fuel System Pressure
Test” and repair fuel system problem if necessary.

Did Fuel System Pressure Test isolate a condition
requiring repair?

—

Verify repair

Go to

Step 15

1. Visually and physically inspect the intake manifold,

injector O-rings, EGR adapter, EGR valve and the
EGR feed pipes for vacuum leaks.

2. Repair any problem that is found.

Did your inspection reveal a problem?

—

Verify repair

Go to

Step 16

Visually and physically inspect the Bank 1 exhaust
manifold for leaks and loose or missing hardware and
correct any problem found.

Did your inspection reveal a problem?

—

Verify repair

Go to

Step 17

Perform the “Injector Balance Test,” and correct any
problem found (refer to

Fuel Metering System).

Did Injector Balance Test isolate a problem?

—

Verify repair

Go to

Step 18

1. Visually and physically inspect the Bank 1 HO2S 1

to ensure that it is installed securely and that the
Bank 1 HO2S 1 pigtail and wiring harness are not
contacting the exhaust or otherwise damaged.

2. If a problem is found, correct it as necessary.

Did your inspection reveal a problem?

—

Verify repair

Refer to

Diagnostic

Aids

Replace the MAF sensor.

Is the action complete?

—

Verify repair

—

6E2–155

6VD1 3.2L ENGINE DRIVEABILITY AND EMISSIONS

Diagnostic Trouble Code (DTC) P0172 Fuel Trim System Rich Bank 1

D06RW068

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

No Tech 2 test is being run.

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.

Engine coolant temperature is between 25

C (77

and 100

C (212

F).

Intake air temperature is between –40

C (–40

F) and

120

C (248

F).

Manifold absolute pressure is between 24 kPa and 99
kPa.

Throttle angle is steady below 95%.

Vehicle speed is below 136 km/h (85 mph).

Engine speed is between 400 and 6000 RPM.

Barometric pressure is greater than 72.5 kPa.

Mass air flow (MAF) is between 2 g/second and 200
g/second.

Ignition voltage is above 9.5 volts.

Fuel system is in “closed loop.”

Canister purge duty cycle is greater than 0%, if “ON.”

Action Taken When the DTC Sets

The PCM will illuminate the malfunction indicator lamp
(MIL) after the second consecutive trip in which 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.

6E2–156

6VD1 3.2L ENGINE DRIVEABILITY AND EMISSIONS

Conditions for Clearing the MIL/DTC

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.

A history DTC P0172 will clear after 40 consecutive
warm-up cycles have occurred without a fault.

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:

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.

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.

6E2–157

6VD1 3.2L ENGINE DRIVEABILITY AND EMISSIONS

DTC P0172 – Fuel Trim System Rich Bank 1

Step

Action

Value(s)

Yes

Was the “On-Board Diagnostic (OBD) System Check”
performed?

—

Go to

Step 2

Go to

OBD

System

Check

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

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

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

Symptoms.

Is DTC P0175 also set?

—

Go to

Step 6

Go to

Step 15

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

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

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

Start the engine and note the idle quality.

Is a low or unsteady idle being experienced?

—

Go to

Step 10

Go to

Step 11

1. Ignition “OFF.”
2. Physically inspect the throttle body bore, throttle

plate, and IAC passages 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

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