Opel Frontera UBS. Manual - part 2145

6E–153

ENGINE DRIVEABILITY AND EMISSIONS

DTC P0152 – HO2S Circuit High Voltage Bank 2 Sensor 1

  (Cont'd)

Step

No

Yes

Value(s)

Action

6

1. Ignition “ON,” engine“OFF.”
2. At Bank 2 HO2S 1 connector (PCM side) jumper

both the HO2S high and low signal circuits (PCM
side) to ground.

3. Using Tech 2, monitor Bank 2 HO2S 1 voltage. 

Is Bank 2 HO2S 1 voltage below the specified value?

10 mV

Go to 

Step 7

Go to 

Step 8

7

1. Disconnect the jumpers to ground from Bank 2

HO2S 1 PCM-side connector. 

2. With the HO2S 1 connector disconnected,  monitor

Bank 2 HO2S 1 voltage.

Is the Bank 2 HO2S 1 voltage between the specified
values?

425-475 mV

Refer to

Diagnostic

Aids 

Go to 

Step 8

8

Replace the PCM.

IMPORTANT: The replacement PCM must be
programmed.  Refer to 

UBS 98model year Immobilizer

Workshop Manual.

Is the action complete?

—

Verify repair

—

6E–154

ENGINE DRIVEABILITY AND EMISSIONS

Diagnostic Trouble Code (DTC) P0171 Fuel Trim System Lean Bank 1

D06RW030

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 1, the PCM will set DTC P0171.
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: EGR DTCs, HO2S DTCs,
(response, transition, open, low volts, no activity), MAF
DTCs, TP sensor DTCs, MAP DTCs, IAT DTCs,
canister purge DTCs, EVAP DTCs, injector circuit
DTCs, or misfire DTCs. 

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 6,000 RPM.

D

Barometric pressure is greater than 72.5 kPa.

6E–155

ENGINE DRIVEABILITY AND EMISSIONS

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.”

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

DTC P0171 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 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 P0171 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. 

6E–156

ENGINE DRIVEABILITY AND EMISSIONS

DTC P0171 – Fuel Trim System Lean 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 P0171 and P0174?

—

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 “BANK 1 L.T. FUEL TRIM”  display on

the Tech 2.

Is the displayed value greater than the specified value?

L.T. Fuel

Trim: +20%

Go to 

Step 5

Go to 

Step 4

4

1. Review and record the 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 “Specific DTC” info for DTC

P0171 while operating the vehicle to duplicate the
Failure Records conditions.

4. Continue operating the vehicle until the DTC P0171

test runs and note the test result.

Does the Tech 2 indicate DTC P0171 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 P0174 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 connections 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 

Step11

10

1. Visually and physically inspect the throttle body,

intake manifold, EGR valve and the EGR feed pipe
for vacuum leaks.

2. Repair any vacuum leaks as necessary.

Did your inspection reveal a vacuum leak?

—

Verify repair 

Go to 

Step 11