catalytic converter AUDI A4 1997 B5 / 1.G APB Engine Oxygen Sensor Control Checking Workshop Manual

24-81


Oxygen sensor and oxygen sensor control
before Three Way Catalytic Converter
(TWC), checking

Special tools and shop equipment

Fluke 83 (or equivalent) A
VAG1594 A
VAG1598/31
VAS5051 with VAS5051/1
- or
VAG1551 with VAG1551/3B
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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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24-93

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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24-95

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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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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Continuation
If specified value in display field 3 or 4 is not
obtained:

- Replace Heated Oxygen Sensor (HO2S) before
Three Way Catalytic Converter Bank 2 -G108.
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24-100


Oxygen sensor and oxygen sensor control
behind catalytic converter, checking

Test equipment and shop tools

Fluke 83 (or equivalent)
VAG1594 A
VAG1598/31
VAG1788/10
VAS5051 with VAS5051/1
- or
VAG1551 with VAG1551/3B
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Notes:

Oxygen sensor control behind the catalytic
converter is responsible for final control
correction. It is the primary sensor and can
override the signal from the oxygen sensor
control before the catalytic converter..

Component location of harness connectors Page 24
-5
It corrects slight changes in the mixture (i.e. enrichment) via the
oxygen sensor before catalytic converter by holding the oxygen
sensor control before catalytic converter at its higher or lower limit for
a specific time (duration). If this time is in the positive range (i.e. 50
ms), mixture is shifted in the -enrich- direction. If this time is in the
negative range (i.e. -50 ms), mixture is shifted in the -lean- direction.
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System in Basic Setting 34
1
2
3
4

When indicated on display:
Note:
This process can take a few minutes. - Adjust engine speed using VAG1788/10 to 2800 - 3200 RPM.
- Continue test as soon as display field 2 indicates an exhaust
temperature of more than 320 C. - Press -C- button.
- Adjust engine speed using VAG1788/10 to 1900 - 2200 RPM.
Basic Settin
g
Q
Input displa
y group number XXX

When indicated on display:
- Press buttons -0-, -3- and -0- to select "display group number 030" and
press -Q- button to confirm input.
System in Basic Setting 30
1
2
3
4

When indicated on display:
Note:
"Oxygen sensor status" indicates status of oxygen sensor control and
oxygen sensor. - Check oxygen sensor status for oxygen sensor behind catalytic
converter in display field 2.
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