Opel Frontera UBS. Manual - part 1195

6E–146

ENGINE DRIVEABILITY AND EMISSIONS

indicates a signal line shorted to ground or signal lines
shorted together.  Disconnect the HO2S and connect
a test light between the HO2S ignition feed and heater
ground circuits.  If the test light does not light for 2
seconds when the ignition is turned on, repair the open
ignition feed or sensor ground circuit as necessary.  If
the test light lights and the HO2S signal and low circuits
are OK, replace the HO2S.

D

Intermittent test – With the Ignition “ON,” monitor the
HO2S signal voltage while moving the wiring harness
and related connectors.  If the fault is induced, the
HO2S signal voltage will change.  This may help isolate
the location of the malfunction.

Test Description

Number(s) below refer to the step number(s) on the
Diagnostic Chart.
3. If the DTC P0134 test passes while the Failure

Records conditions are being duplicated, an
intermittent conditions is indicated.

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.

DTC P0134 –HO2S Circuit  Insufficient Activity Bank 1 Sensor 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

1. Install Tech 2.
2. Run the engine at operating temperature.
3. Operate the engine above 1200 RPM for two

minutes.

Does Tech 2 indicate Bank 1 HO2S 1 voltage varying
outside the specified values?

400-500 mV

Go to 

Step 3

Go to 

Step 4

3

1. Ignition “ON,” engine “OFF,” review and record Tech

2 Failure Records data and note parameters.

2. Operate the vehicle within Failure Records

conditions as noted.

3. Using Tech 2, monitor “Specific DTC” info for DTC

P0134 until the DTC P0134 test runs.

4. Note the test result.

Does Tech 2 indicate DTC P0134 failed this ignition?

—

Go to 

Step 4

Refer to

Diagnostic

Aids

4

Check for a damaged harness.

Was a problem found?

—

Verify repair

Go to 

Step 5

5

Check for poor Bank 1 HO2S 1 high and low circuit
terminal connections at the Bank 1 HO2S 1 harness
connector and replace terminal(s) if necessary.

Did any terminals require replacement?

—

Verify repair

Go to 

Step 6

6

Check for poor Bank 1 HO2S 1 high and low circuit
terminal connections at the PCM and replace terminals
if necessary.

Did any terminals require replacement?

—

Verify repair

Go to 

Step 7

7

1. Ignition “OFF.”
2. With the PCM disconnected, check continuity of the

Bank 1 HO2S 1 high circuit.

3. If the Bank 1 HO2S 1 high circuit measures over 5.0

ohms, repair open or poor connection as necessary.

Was a Bank 1 HO2S 1 high circuit problem found and
corrected?

—

Verify repair

Go to 

Step 8

6E–147

ENGINE DRIVEABILITY AND EMISSIONS

DTC P0134 –HO2S Circuit  Insufficient Activity Bank 1 Sensor 1

  (Cont'd)

Step

No

Yes

Value(s)

Action

8

1. Ignition “OFF.”
2. With the PCM disconnected, check continuity of the

Bank 1 HO2S 1 low circuit.

3. If the Bank 1 HO2S 1 low circuit measures over 5

ohms, repair open or poor connection as necessary.

Was a Bank 1 HO2S 1 low circuit problem found and
corrected?

—

Verify repair

Go to 

Step 9

9

1. Ignition “ON,” engine “OFF.”
2. Disconnect Bank 1 HO2S 1 and jumper the HO2S

high and low circuits (PCM side) to ground.

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

Is Bank 1 HO2S 1 voltage in the specified range?

0-10 mV

Go to 

Step 10

Go to 

Step 11

10

Replace Bank 1 HO2S 1.

Is the action complete?

—

Verify repair

—

11

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–148

ENGINE DRIVEABILITY AND EMISSIONS

Diagnostic Trouble Code (DTC) P0151 HO2S Circuit Low Voltage Bank 2 

Sensor 1

060RW190

Circuit Description

The powertrain control module (PCM) supplies a bias
voltage of about 450 mV between the heated oxygen
sensor (HO2S) signal high and signal low circuits.  When
measured with a 10 megaohm digital voltmeter, this may
display as low as 320 mV.  The oxygen sensor varies the
voltage within a range of about 1000 mV when the
exhaust is rich, down through about 10 mV when exhaust
is lean.  The PCM constantly monitors the HO2S signal
during “closed loop” operation and compensates for a rich
or lean condition by decreasing or increasing injector
pulse width as necessary.  If the Bank 2 HO2S 1 voltage
remains excessively low for an extended period of time,
DTC P0151 will be set.

Conditions for Setting the DTC

D

No related DTCs.

D

The engine is operating in “closed loop.”

D

Engine coolant temperature is above 60

°

C (140

°

F).

D

“Closed loop” commanded air/fuel ratio is between
14.5 and 14.8.

D

Throttle angle is between 3% and 19%.

D

Bank 2 HO2S 1 signal voltage remains below 22 mV
during normal “closed loop” operation for a total of 77
seconds over a 90-second period of time.

Action Taken When the DTC Sets

D

The PCM will illuminate the malfunction indicator lamp
(MIL) the first time 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.

D

“Open loop” fuel control will be in effect.

Conditions for Clearing the MIL/DTC

D

DTC P0151 can be cleared by using Tech 2 “Clear Info”
function or by disconnecting the PCM battery feed.

Diagnostic Aids

Check for the following conditions:

D

Heated oxygen sensor wiring – The sensor pigtail may
be mispositioned and contacting the exhaust system.

D

Poor PCM to engine block grounds.

D

Fuel pressure – The system will go lean if pressure is
too low.  The PCM can compensate for some
decrease.  However, if fuel pressure is too low, a DTC
P0151 may be set.  Refer to 

Fuel System Diagnosis.

D

Lean injector(s) – Perform “Injector Balance Test.”

D

Vacuum leaks – Check for disconnected or damaged
vacuum hoses and for vacuum leaks at the intake
manifold, throttle body, EGR system, and PCV system.

D

Exhaust leaks – An exhaust leak may cause outside air
to be pulled into the exhaust gas stream past the
HO2S, causing the system to appear lean.  Check for

6E–149

ENGINE DRIVEABILITY AND EMISSIONS

exhaust leaks that may cause a false lean condition to
be indicated.

D

MAF sensor –The system can go lean if the MAF
sensor signal indicates an engine airflow
measurement that is not correct. Disconnect the MAF
sensor to see if the lean condition is corrected.  If so,
replace the MAF sensor.

D

Fuel contamination – Water, even in small amounts,
can be delivered to the fuel injectors.  The water can
cause a lean exhaust to be indicated.  Excessive
alcohol in the fuel can also cause this condition.  Refer
to 

Fuel System Diagnosis for the procedure to check

for fuel contamination.

D

If none of the above conditions are present, replace the
affected HO2S.

Test Description

Number(s) below refer to the step number(s) on the
Diagnostic Chart.
3. DTC P0151 failing during operation may indicate a

condition described in the “Diagnostic Aids” above.
If the DTC P0151 test passes while the Failure
Records conditions are being duplicated, an
intermittent condition is indicate.

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.

DTC P0151 – HO2S Circuit Low Voltage Bank 2 Sensor 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

1. Install Tech 2.
2. Run the engine at operating temperature.
3. Operate the vehicle within the parameters specified

under “Conditions for Setting the DTC” criteria
included in Diagnostic Support.

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

Does the Bank 2 HO2S 1 voltage remain below the
specified value?

22 mV

Go to 

Step 4

Go to 

Step 3

3

1. Ignition “ON,” engine “OFF,” review and record Tech

2 Failure Records data and note parameters.

2. Operate the vehicle within Failure Records

conditions as noted.

3. Using Tech 2, monitor “Specific DTC” info for DTC

P0151 until the DTC P0151 test runs.

4. Note test result.

Does Tech 2 indicate DTC P0151 failed this ignition?

—

Go to 

Step 4

Refer to

Diagnostic

Aids

4

1. Turn ignition “OFF.”
2. Disconnect the PCM.
3. Check the Bank 2 HO2S 1 high and low signal

circuits for a short to ground or a short to the heater
ground circuit.

Were Bank 2 HO2S 1 signal circuits shorted?

—

Go to 

Step 5

Go to 

Step 6

5

Repair the Bank 2 HO2S 1 signal circuit.

Is the action complete?

—

Verify repair

—

6

1. Ignition “OFF.”
2. Leave the PCM and HO2S 1 disconnected.
3. Check for continuity between the high and low

signal circuits.

Was there continuity between the high and low circuits?

—

Go to 

Step 7

Go to 

Step 8

7

Repair the short between the high and low circuits.

Is the action complete?

—

Verify repair

—