Opel Frontera UE. Manual - part 338

 

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Opel Frontera UE. Manual - part 338

 

 

6E2–158

6VD1 3.2L ENGINE DRIVEABILITY AND EMISSIONS

DTC P0172 – Fuel Trim System Rich Bank 1

  (Cont'd)

Step

No

Yes

Value(s)

Action

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 TP 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 0%

Maximum

100%

Go to 

Step 13

Go to 

Step 20

13

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

monitoring the “B1 Long Term Fuel Trim” and “B1
Short Term Fuel Trim” display on the Tech 2.

Did both values change to near the specified value?

0%

Go to 

Step 21

Go to 

Step 14

14

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 15

Go to 

Step 18

15

Check for short to ground in the wire (red/blue)
between the canister purge solenoid and PCM terminal
A-15.

Was there a short to ground?

Go to 

Step 16

Go to 

Step 17

16

Repair the short to ground.

Is the action complete?

Verify repair

17

Replace the PCM.

Is the action complete?

Verify repair

18

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 19

19

1. Remove and visually/physically inspect the Bank 1

HO2S 1 for silicon contamination.  This will be
indicated by a powdery white 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

Refer to

Diagnostic

Aids

20

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

21

Replace the MAF sensor.

Is the action complete?

Verify repair

6E2–159

6VD1 3.2L ENGINE DRIVEABILITY AND EMISSIONS

Diagnostic Trouble Code (DTC) P0174 Fuel Trim System Lean Bank 2

D06RW069

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
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 lean condition is detected on
Bank 2, the PCM will set DTC P0174.
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 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

No Tech 2 test is being run.

D

None of the following DTCs are set: idle system, EGR,
HO2S, (response, transition, open, low volts, no
activity), MAF, TP sensor, MAP, IAT, canister purge,
EVAP, injector circuit, or misfire.

D

Engine coolant temperature is between 25

°

C (77

°

F)

and 100

°

C (212

°

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 6000 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 15%, 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
failure 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.

D

A history DTC P0174 will clear after 40 consecutive
warm-up cycles have occurred without a fault.

6E2–160

6VD1 3.2L ENGINE DRIVEABILITY AND EMISSIONS

D

DTC P0174 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 2 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 P0171 and P0174 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 P0171/P0174.

4. If the DTC P0174 test passes while the Failure

Records conditions are being duplicated, the lean
condition is intermittent.  Refer to 

Diagnostic Aids or

Symptoms for additional information on diagnosing
intermittent problems.

6E2–161

6VD1 3.2L ENGINE DRIVEABILITY AND EMISSIONS

DTC P0174 – Fuel Trim System Lean Bank 2

 

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 P0174 and P0171?

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 the “B2 Long Term Fuel Trim” display on

the Tech 2.

Is the displayed values greater than the specified
values?

L.T. Fuel

Trim: +20%

Go to 

Step 5

Go to 

Step 4 

4

1. Review and record Tech 2 Failure Records data.
2. Clear the DTC P0171/P0174 and operate the

vehicle to duplicate the Failure Records conditions.

3. Monitor the Tech 2 “DTC” info for DTC P0174 while

operating the vehicle to duplicate the Failure
Records conditions.

4. Continue operating the vehicle until the DTC P0174

test runs.

5. Note the test result.

Does the Tech 2 indicate DTC P0174 failed this
ignition?

Go to 

Step 5

The lean

condition is

not present.

If a

driveability

symptom still

exists, refer

to 

Symptoms

section.

5

Was DTC P0171 also set?

Go to 

Step 6

Go to 

Step 15

6

Visually and physically inspect the vacuum hoses for
disconnects, splits, kinks, improper routing and
improper disconnections and repair any problem
found.

Did your inspection reveal a problem requiring repair?

Verify repair 

Go to 

Step 7

7

Visually and physically inspect the crankcase
ventilation valve for proper installation and repair any
problem found (refer to 

Crankcase Ventilation

System).

Did your inspection reveal a problem requiring repair?

Verify repair

Go to 

Step 8

8

1. Inspect the MAF sensor inlet screen for damage or

for the presence of foreign objects which may
partially block the air flow sample through the MAF
sensor.

2. Correct any problem that is found as necessary.

Did your inspection of the MAF sensor reveal a
condition requiring repair?

Verify repair

Go to 

Step 9

9

Start the engine and note the idle quality.

Is a high or unsteady idle being experienced?

Go to 

Step 10

Go to 

Step 11

 

 

 

 

 

 

 

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