1999 AUDI A4 sensor

before catalytic converter (bank 1)
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Oxygen sensor and oxygen sensor control
behind catalytic converter, checking

Special Tools and Equipment

VAG1526A
VAG1594A
VAG1598/31
VAG1788/10 RPM adjuster
VAS5051 with VAG5051/1
- or
VAG1551 with VAG1551/3B
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Notes:

The oxygen sensor control behind catalytic
converter overrules the oxygen sensor control
before catalytic converter. It serves as a
corrective control.

Test requirements:
Test sequence
It corrects slight changes in the mixture (i.e. enrichment) via the
oxygen sensor before catalytic converter by holding oxygen sensor
control before catalytic converter at its higher or lower point for a
specific time (dwell time). If this time is in the positive range (i.e. 50
ms), mixture is shifted in the -enrich- direction. If it is in the negative
range (i.e.--50 ms), mixture is shifted in the -lean- direction. Road test performed and DTC memory erased. Coolant temperature at least 80 C Display group 4, display field 3
- Connect VAS5051 tester or VAG1551 scan tool and select the control
module for engine electronics using "address word" 01 Page 01
-9 .
Engine must run at idle for this.
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Rapid data transfer
HELP
Select function XX

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

When indicated on display:
- Press buttons -0-, -3- and -4- to select "display group number 034" and
press -Q- button to confirm input.
System in Basic Setting 34
1
2
3
4

When indicated on display:
Note:
This process can take a few minutes. - Use VAG1788/10 RPM adjuster to adjust engine speed to between
2800 and 3200 RPM.
- Continue test as soon as display field 2 indicates an exhaust
temperature of more than 380 C
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- Press -C- button.

- Let engine continue to idle Basic Setting
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 sensors. - Check oxygen sensor status for oxygen sensor behind catalytic
converter in display fields 2 and 4.
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Display fields

1 2 3 4
Display group 030: Oxygen sensor status with engine at idle
Display X X X
X X X X X X
X X X
Indicated Oxygen sensor status, bank 1,
sensor 1 Oxygen sensor
status
Bank 2, sensor 1 Oxygen sensor status, bank 2,
sensor 1 Oxygen sensor
status
Bank 2, sensor 2
Functional
range 0 = off
1 = on 0 = off
1 = on 0 = off
1 = on 0 = off
1 = on
Specified
value 1 1 1
1 1 0 1 1 1
1 1 0
Notes
Meaning of display Page 24
-102

If specified value is not obtained Page 24
-111

If specified value is obtained but there is a malfunction stored in DTC memory Check oxygen
sensor control, page Page 24
-105

Notes:

Oxygen sensor control of oxygen sensor behind catalytic converter (bank 1 sensor 2 and bank 2 sensor 2) are not active
without engine load, meaning that the display is 0.
The first position of the 3 digit indication (heating) fluctuates between 0 and 1.
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The third position of the 3 digit indication (oxygen sensor control) fluctuates between 0 and 1.
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Significance of 3 digit indication of display group 030 X
X
X
Display fields 1 to 4
X Oxygen sensor control
0= not active
1 = active
X Operational readiness of oxygen sensor
0= not active
1 = active
X Condition of oxygen sensor heating
0= not active
1 = active

- Press -C- button.Basic Setting
Q
Input displa
y group number XXX

When indicated on display:
- Press buttons -0-, -4- and -3- to select "display group number 043" and press -Q-
button to confirm input.
System in Basic Setting 43
1
2
3
4

When indicated on display:
- Check specified value in display field 4 after indication "Test ON" appears:
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