engine AUDI A4 1995 B5 / 1.G APB Engine Oxygen Sensor Control Checking Workshop Manual

24-80
If the voltage does not change or only changes
slowly the following malfunctions are possible:

Slits or holes in probe head are blocked.
Oxygen sensor has been subjected to
excessive thermal stress.
Contact resistance in signal wire or Ground
(GND) wire.
Oxygen sensor too cold; sensor heater not
working.
Oxygen sensor damaged by contact spray or
similar product. (The contact spray is drawn
through the fine cavities in the electrical wiring
as a result of thermal fluctuations and capillary
effect.)
Oxygen sensor damaged by silicone vapors.
(The engine draws in traces of any silicone-
based sealants that may have been used. The
silicone does not burn and damages the oxygen
sensor.)
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Checking function

- Connect vehicle diagnostic, testing and
information system VAS5051 or VAG1551 scan
tool and select engine electronics control
module by entering address word "01" Page
01
-9 . When doing this the engine must be at
idle.
Rapid data transfer
HELP
Select function XX

Indicated on display
Note:
During the basic setting the Evaporative Emission (EVAP) canister purge
regulator valve -N80 is closed and the A/C compressor is switched off. - Press buttons -0- and -4- to select function "Basic Setting" and confirm
entry with -Q- button.
Basic Settin
g
Input displa
y group number XXX

Indicated on display
- Press buttons -0-, -3- and -0- to select "display group number 030" and
confirm entry with -Q- button.
System in Basic Setting 30
1
2
3
4

Indicated on display: (1 - 4 display fields) - Check oxygen sensor status in display fields 1 to 4.
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24-85
Significance of 3 digit indication in Display Group 30 1
1
1
Display fields 1 through 3
X Oxygen sensor control
0= inactive
1= active
X Operational readiness of oxygen sensor
0= inactive
1= active
X Condition of oxygen sensor heater
0= inactive
1= active
Note:

The oxygen sensor control for oxygen sensors behind the catalytic converter (B1-S2 and B2-S2) are without engine load
at certain operating conditions not active, that means, the third place of oxygen sensor control for oxygen sensors behind
the catalytic converter can fluctuate between 0 and 1.
The first position of the 3 digit display (Heater) fluctuate at certain operating conditions between 0 and 1.
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24-86

Checking oxygen sensor adaptation and
oxygen sensor control

- Connect vehicle diagnostic, testing and
information system VAS5051 or VAG1551 and
select engine electronics control module by
entering address word "01" Page 01
-9. When
doing this the engine must be idling.
Rapid data transfer
HELP
Select function XX

Indicated on display
Note:
During the basic setting the Evaporative Emission (EVAP) canister purge
regulator valve -N80 is closed and the A/C compressor is switched off. - Press buttons -0- and -4- to select function "Basic Setting" and confirm
entry with -Q- button.
Basic Settin
g
Input displa
y group number XXX

Indicated on display
- Press buttons -0-, -3- and -3- to select Display Group 33 and confirm
entry with -Q- button.
System in Basic Setting 33
1
2
3
4

Indicated on display: (1 - 4 display fields)
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24-93

Oxygen sensors aging, oxygen sensor
before catalytic converter, checking


Test requirements

Coolant temperature min. 85 C (185 F)
(Display group 004, display field 3)

Test sequence for oxygen sensor 1 before
catalytic converter bank 1

- Connect vehicle diagnostic, testing and
information system VAS5051 or VAG1551 and
select engine electronics control module by
entering address word "01" Page 01
-9. When
doing this the engine must be at idle.
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Rapid data transfer
HELP
Select function XX

Indicated on display
- Press buttons -0- and -4- to select "Basic Setting" and confirm with -Q-
button.
Basic Setting
Q
Input displa
y group number XXX

Indicated on display
Test requirements - Press -0-, -3- and -4- to select "display group number 034" and confirm
with -Q- button.
Engine runs at 1900 - 2200 RPM
System in Basic Setting 34
1
2
3
4

Indicated on display
- Continue test as soon as display field 4 indicates "Test ON".
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Note:
This procedure can take a few minutes

Display fields

1 2 3 4
Display field 034: Diagnostic oxygen sensor aging (Bank 1)
Display xxxx/RPM
xxx C
x.x s
Test ON
Indicated Engine speed
(RPM) Exhaust
temperature Period duration
oxygen sensor before catalytic
converter Diagnostic condition
Working
range 0 - 6800
70 - 850 C
0 - 3.0 Seconds
Test OFF
Test ON
B1-S1 OK
B1-S1 not OK
Specification 1900 - 2200/RPM greater than 260
C
0.1 - 1.0 s
B1-S1 OK
Note


If specified value is not obtained Continuation Page
Page 24
-96

Note for display field 2:
Calculated value from engine speed and engine load.
Note for display fields 3 and 4:
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Continuation
If specified value in display field 3 or 4 is not
obtained:

- Replace Heated Oxygen Sensor (HO2S) before
Three Way Catalytic Converter Bank 1 -G39.

Test sequence for oxygen sensor 1 before
catalytic converter bank 2

- Connect vehicle diagnostic, testing and
information system VAS5051 or VAG1551 and
select engine electronics control module by
entering address word "01" Page 01
-9. When
doing this the engine must be at idle.
Rapid data transfer
HELP
Select function XX

Indicated on display
- Press buttons -0- and -4- to select "Basic Setting" and confirm with -Q-
button.
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Basic Settin
g
Q
Input display group number XXX

Indicated on display
Test requirements - Press -0-, -3- and -5- to select "display group number 035" and confirm
with -Q- button.
Engine runs at 1900 - 2200 RPM
System in Basic Setting 35
1
2
3
4

Indicated on display
Note:
This procedure can take a few minutes - Continue test as soon as display field 4 indicates "Test ON".
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Display fields

1 2 3 4
Display field 035: Diagnostic oxygen sensor aging (Bank 2)
Display xxxx/RPM
xxx C
x.x s
Test ON
Indicated Engine speed
(RPM) Exhaust
temperature Period duration oxygen sensor before
catalytic converter Diagnostic
condition
Working
range 0 - 6800
70 - 850 C
0 - 3.0 Seconds
Test OFF
Test ON
B1-S1 OK
B1-S1 not OK
Specification 1900 - 2200/RPM greater than 260
C
0.1 - 1.0 s
B1-S1 OK
Note


If specified value is not obtained Continuation Page
Page 24
-99

Note for display field 2:
Calculated value from engine speed and engine load.
Note for display fields 3 and 4:
Period duration is the time between two voltage jumps (e.g. rich - lean - rich) and is therefore a measurement of the aging
condition of the oxygen sensor. If the specified time is exceeded, display field 4 will indicate =B2-S1 not OK.
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