AUDI A4 1995 B5 / 1.G APB Engine Oxygen Sensor Control Checking Owner's Guide
Manufacturer: AUDI, Model Year: 1995, Model line: A4, Model: AUDI A4 1995 B5 / 1.GPages: 61, PDF Size: 0.27 MB
Page 31 of 61

24-106
Display fields
1 2 3
4
Display group 043: Oxygen sensor aging oxygen sensor behind catalytic converter (Bank 1)
Display xxxx/RPM
xxx C
x.xxx V
Test ON
Indicated Engine speed
(RPM) Exhaust
temperature Voltage of oxygen sensor
behind CAT, Bank 1 Diagnostic condition
Work range 0 - 6800/RPM
70 - 850 C
0.000 - 1.000 Volt
Test OFF
Test ON
B1-S2 OK
B1-S2 not OK
Specified
value 1900 -
2200/RPM greater than 320
C 0.000 - 1.000 Volt
B1-S2 OK
Note
If specified value is not reached. Check
oxygen sensor heater Page 24
-114
If the specified value of "B1-S2 OK" is reached:
- Press -C- button.
Test requirements
Engine runs at 1900 - 2200 RPM
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Page 32 of 61

- Press buttons -0-, -4- and -4- to select "display
group number 044" and press -Q- button to
confirm input.
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Page 33 of 61

24-107
Display fields
1 2 3
4
Display group 044: Oxygen sensor aging oxygen sensor behind catalytic converter (Bank 2)
Display xxxx/RPM
xxx C
x.xxx V
Test ON
Indicated Engine speed
(RPM) Exhaust
temperature Voltage of oxygen sensor
behind CAT, Bank 1 Diagnostic condition
Work range 0 - 6800/RPM
70 - 850 C
0.000 - 1.000 Volt
Test OFF
Test ON
B2-S2 OK
B2-S2 not OK
Specified
value 1900 -
2200/RPM greater than 320
C 0.000 - 1.000 Volt
B1-S2 OK
Note
If specified value is not reached. Check
oxygen sensor heater Page 24
-114
If the specified value of "B2-S2 OK" is reached:
- Press -C- button.
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Page 34 of 61

24-108
Checking oxygen sensor control behind
catalytic converter
- Carry out road test for approx.: 10 minutes.Basic Setting
Q
Input displa
y group number XXX
Indicated on display
- Press buttons -0-, -3- and -7- to select "display group number 037" and
press -Q- button to confirm input.
System in Basic Setting 37
1
2
3
4
Indicated on display
- Check oxygen sensor voltage in display field 2.
- Check dwell time (hold up) between oxygen sensor 1 before catalytic
converter and oxygen sensor 2 behind catalytic converter in display
field 3 and diagnostic result in display field 4.
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Page 35 of 61

24-109
Display fields
1 2 3 4
Display group 037: Diagnostic oxygen sensor control (Bank 1)
Display xxx % x.xxx Volt xxx ms
Test ON
Indicated Engine
load Oxygen sensor voltage behind
catalytic converter, Bank 1 Correction value between
oxygen sensor 1 and sensor
2, bank 1 Diagnostic condition
Work
range 15.0 -
175.0 % 0.000 - 1.000 V -1200 - 1200 ms
Test OFF
Test ON
SYST. OK
SYST. not OK
Specified
value 15.0 -
25.0 % 0.000 - 1.000 V -500 - 500 ms
SYST. OK
Note
If specified value is not
obtained: Evaluation display
field 2 Page 24
-112
If specified value is
obtained: Continuation
Page 24
-113
If "SYST. not OK" is
displayed: Check DTC
memory Page 01
-15
or Continue Page 24-113
Note for display field 3:
Oxygen sensor control behind catalytic converter is superior to oxygen sensor control before catalytic converter and is the
primary control. It corrects slight changes in the mixture (i.e. enrichment or thinning) by holding the oxygen sensor control
before catalytic converter at its higher or lower point 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-
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Page 36 of 61

direction.
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Page 37 of 61

24-110
- Press -C- button.
- Press buttons -0-, -3- and -8- to select "display
group number 038" and press -Q- button to
confirm input. System in Basic Setting 38
1
2
3
4
Indicated on display: (1 - 4 display fields)
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Page 38 of 61

24-111
Display fields
1 2 3 4
Display group 038: Diagnostic oxygen sensor control (Bank 2)
Display xxx % x.xxx Volt xxx ms
Test ON
Indicated Engine
load Oxygen sensor voltage behind
catalytic converter, Bank 2 Correction value between
oxygen sensor 1 and sensor
2, bank 2 Diagnostic condition
Work
range 15.0 -
175.0 % 0.000 - 1.000 V -1200 - 1200 ms
Test OFF
Test ON
SYST. OK
SYST. not OK
Specified
value 15.0 -
25.0 % 0.000 - 1.000 V -500 - 500 ms
SYST. OK
Note
If specified value is not obtained:
Evaluation display field 2
Page 24
-112
If specified value is obtained:
Continuation Page 24
-113
If "SYST. not OK" is
displayed: Check DTC
memory Page 01
-15
or Continue Page 24-113
Note for display field 3:
Oxygen sensor control behind catalytic converter is superior to oxygen sensor control before catalytic converter and is the
primary control. It corrects slight changes in the mixture (i.e. enrichment or thinning) by holding the oxygen sensor control
before catalytic converter at its higher or lower point 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-
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Page 39 of 61

direction.
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Page 40 of 61

24-112
Evaluation display group 037 and 038 Display Group:
037/038
Display field: 2
Possible cause
Corrective action
approx.: 0.450 V
Open circuit in wire 4 between oxygen sensor
and control module - Check signal wire and activation Page 24
-
122
Open circuit in wire 3 between oxygen sensor
and control module
Oxygen sensor heater faulty
Oxygen sensor faulty- Check oxygen sensor heater Page 24
-114
- Replace oxygen sensor
greater than
1.100 V
Short circuit to B+ in wire 4 between oxygen
sensor and control module - Check oxygen sensor wiring bank 1 sensor 2
(behind converter) Page 24
-125
smaller than
0.100 V
Short circuit to Ground (GND) in wire 4 between
oxygen sensor and control module
Short circuit between wire 3 and 4- Check oxygen sensor wiring bank 2 sensor 2
(behind converter) Page 24
-129
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