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

24-82

Notes:

For the defined troubleshooting procedure, it is
possible to switch off the oxygen sensor control
by selecting Display Group 99 in "Basic Setting"
mode and to switch it on again by selecting
Display Group 99 in "Read Measuring Value
Block" mode.
After selecting Display Group 99 (either in
"Basic Setting" mode or in "Read Measuring
Value Block" mode) it is possible to switch back
and forth between function 04 ("Basic Setting")
and function 08 "Read Measuring Value Block")
by pressing buttons 4 and 8 on VAG1551 scan
tool.
When exiting the "Basic Setting" mode (function
04) the oxygen sensor control is automatically
switched on again.

Test conditions
Perform road test and do not erase DTC
memory.
Coolant temperature at least 85 C (Display
group 004, display field 3)
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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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24-95

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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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 =B1-S1 not OK.
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24-98


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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24-102

Test conditions

Perform road test and do not erase DTC
memory.
Coolant temperature at least 85 C (185 F)
(Display group 004, display field 3)

- 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 -4- to select "display group number 034" and
confirm entry with -Q- button.
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24-105
Significance of 3 digit indication in Display Group 030 1
1
1
Display fields 1 to 4
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

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

When indicated on display
Test requirements - Press buttons -0-, -4- and -3- to select "display group number 043" and press -Q-
button to confirm input.
Engine runs at 1900 - 2200 RPM
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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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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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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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