check engine light AUDI A8 1996 D2 / 1.G ATQ Engine Oxygen Sensor Control Checking

24-98

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.
Pa
ge 27 of 63 Ox
yg
en sensor control, checkin
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11/23/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU05.24.3

24-106


Display fields

1 2 3 4
Display group 037: Diagnostic, oxygen sensor control system (bank 1)
Display xxx % x.xxx volts
xxx ms
---
Indicated Engine
load Oxygen sensor voltage
behind catalytic
converter, bank 1 Oxygen sensor correction
value between oxygen sensor
1 and oxygen sensor 2, bank 1 Diagnostic condition
Functional
range 12.0 to
100.0 % 0.100 to 1.000 V
-800 to 800 ms
Test OFF
Test ON
System OK
System not OK
Specified
value 12.0 to
26.0 % 0.100 to 1.000 V
-800 to 800 ms System OK
Notes
If specified value is not
obtained: Evaluation
display field 2
Page 24
-109

If specified value is not
obtained Page 24
-110

If "System not OK" is displayed:
Check Diagnostic Trouble Code
(DTC) memory Page 01
-15

or continuation Page 24
-110

Note for display field 3:
The oxygen sensor control behind catalytic converter overrules the oxygen sensor control before catalytic converter. It
corrects slight changes in the mixture (i.e. toward rich or lean) due to 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 this time is in the negative range (i.e. -50 ms), mixture
Pa
ge 37 of 63 Ox
yg
en sensor control, checkin
g
11/23/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU05.24.3

24-108


Display fields

1 2 3 4
Display group 038: Diagnostic of oxygen sensor control system (Bank 2)
Display xxx % x.xxx V xxx ms
---
Indicated Engine
load Oxygen sensor voltage
behind catalytic converter,
bank 2 Oxygen sensor correction
value between oxygen sensor
2 and oxygen sensor 2, bank
1 Diagnostic condition
Functional
range 12.0 to
100.0 % 0.100 to 1.000 V -800 to 800 ms
System OK
System not OK
Specified
value 12.0 to
26.0 % 0.100 to 1.000 V -800 to 800 ms System OK
Notes
If specified value is not
obtained: Evaluation
display field 2 Page 24
-
109

If specified value is not
obtained Page 24
-110

If "SYST not OK" is displayed:
Check Diagnostic Trouble Code
(DTC) memory Page 01
-15

or continuation
Page 24
-110

Note for display field 3:
The oxygen sensor control behind catalytic converter overrules the oxygen sensor control before catalytic converter. It
corrects slight changes in the mixture (i.e. toward rich or lean) due to 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 this time is in the negative range (i.e. -50 ms), mixture
is shifted in the -lean- direction.
Pa
ge 40 of 63 Ox
yg
en sensor control, checkin
g
11/23/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU05.24.3