check engine AUDI A4 1995 B5 / 1.G ATW Engine Oxygen Sensor Control Workshop Manual

24-72

Test requirements:

Exhaust system free of leaks.
Coolant Temperature at least 80 C.

Test sequence

- Connect VAS5051 tester or VAG1551 scan tool
and select control module for engine electronics
using "address word" 01 Page 01
-10
. Engine
must run at idle.
Rapid data transfer
HELP
Select function XX

When indicated on display
- Press buttons -0- and -4- to select "Initiate basic setting" and press -Q-
button to confirm input.
Basic Settin
g
Q
Enter displa
y group number XXX

When indicated on display
Note: - Press buttons -0-, -3- and -0- to select "display group number 030" and
press -Q- button to confirm input.
- Check specified value in display field 1.
Increase engine speed to obtain specified values faster. "Oxygen sensor status" indicates status of oxygen sensor control and
oxygen sensors.
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- Connect VAG1598/31 test box at wiring harness
to Engine Control Module (ECM), do not connect
ECM Page 24
-19
.

If wire connection is OK: - Check following wire connections for open circuit.Harness connector
Terminal
VAG1598/31 test box
Socket
3 51
4 70
- Repair open circuit if necessary.
- Check wires to each other for short circuit.
- Replace Engine Control Module (ECM) Page 24
-23
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Test sequence

- Connect VAS5051 tester or VAG1551 scan tool
and select control module for engine electronics
using "address word" 01 Page 01
-10
. Engine
must run at idle.
Rapid data transfer
HELP
Select function XX

When indicated on display
- Press buttons -0- and -4- to select "Initiate basic setting" and press -Q-
button to confirm input.
Basic Settin
g
Q
Enter 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
1800 and 2200 RPM.
- Check specified value in display field 4:
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Display fields

1 2 3 4
Display group 034: Diagnostic oxygen sensor aging
Display xxxx/min
xxx C
x.x s
---
Indicated Engine speed
(RPM) Exhaust
temperature Period duration Oxygen sensor before
Catalytic converter Diagnostic
condition
Functional
range

Test OFF
Test ON
B1-S2 OK
B1-S2 not OK
Specified
value 1800 to 2200
RPM more than 350 C
0.0 to 1.0 s B1-S2 OK
Note


If specified value is not obtained Continuation, Page 24
-
86

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 oxygen sensor 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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24-89

Test requirements:

Road test performed and DTC memory
erased.
Coolant Temperature at least 80 C.

Test sequence

- Connect VAS5051 tester or VAG1551 scan tool
and select control module for engine electronics
using "address word" 01 Page 01
-10
. Engine
must run at idle.
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
Enter 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.
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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. - 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 350 C. - Press -C- button.
- Use VAG1788/10 RPM adjuster to adjust engine speed to between
1800 and 2200 RPM.
Basic Setting
Q
Enter 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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Display fields

1 2 3 4
Display group 030: Oxygen sensor status with engine at idle
Display X X X
X X X

Indicated Oxygen sensor status, bank 1, sensor 1
Oxygen sensor status Bank 2, sensor 1

Functional range 0 = off
1 = on 0 = off
1 = on

Specified value 1 1 1
1 1 0

Note
If specified value is not obtained Page 24
-99

Significance of 3 digit indications in display group 030 X
X
X
Display fields 1 and 2
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 heater: 0= not active; 1 = active
Note:

Oxygen sensor control of oxygen sensor behind catalytic converter (B1-S2) is not active without engine load.
The first position of the 3 digit indication (heating) fluctuates between 0 and 1.
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Display fields

1 2 3 4
Display group 037: Diagnostic oxygen sensor control system
Display xxx %
x.xxx volts
xxx ms
---
Indicated Engine
load Oxygen sensor voltage
Bank 2, sensor 1 Dwell time, oxygen sensor control
before catalytic converter, bank 1 Diagnostic condition
Functional
range


Test OFF
Test ON
System OK
System not OK
Specified
value 15 to 33
% 0.100 to 0.900 V
-150 to 150 ms System OK
Note

If specified value is not
obtained: Evaluation display
field 2 Page 24
-94

If value climbs to above 300 ms,
this indicates a leaking exhaust
system or faulty oxygen sensor If "SYST not OK" is
displayed: Check DTC
memory Page 01
-16

Note for display field 3:
Oxygen sensor control behind catalytic converter is superior to oxygen sensor control before catalytic converter and is
responsible for control correction. 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.
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Checking oxygen sensor wires

Note:
Coolant reservoir screws must be removed and coolant reservoir must be
placed to side in order to access the harness connector. The coolant
hoses can remain connected. - Disconnect 4-pin harness connector -1- (brown) to Oxygen Sensor
(O2S) behind Three Way Catalytic Converter (TWC) -G130-.
- Connect VAG1598/31 test box at wiring harness to Engine Control
Module (ECM), do not connect ECM Page 24
-19
.

- Check following wire connections for open circuit.Harness connector
Terminal
VAG1598/31 test box
Socket
3 68
4 69
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- Repair open circuit if necessary.

- Check wires to each other for short circuit.
If wire connection is OK:

- Replace Engine Control Module (ECM) Page
24
-23

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