1995 AUDI A4 engine

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Test requirements:

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

Test sequence

- Connect VAS5051 tester Page 01
-7 and
select vehicle system "01 - Engine electronics".
Engine must run at idle for this.

Display on VAS5051:
- In selection -1-, click on the diagnostic function "04 - Basic setting".
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Display on VAS5051:
1 - Enter display group Max. input value = 255
- Select function "030" in button field -2- for "display group number 030"
and press Q button to confirm input.

Display on VAS5051:
Notes: - 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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-
Press button to change into display group
033.
- Check oxygen sensor control in display fields -1-
and -2-.

Display fields

1 2 3 4
Display group 033: Oxygen sensor control
Display
xx.x %
x.xxx V


Indicated
Oxygen sensor control bank 1, sensor 1
Oxygen sensor voltage, Bank 1, sensor 1

Specified
value Value must fluctuate at least 2 % in the
range -10.0 to 10.0 % 0.130 to 3.600 volts


Note
If specified value is not obtained
Continuation, Page 24
-77

If specified value is not obtained Evaluation
display group 033, Page 24
-80



Note for display field 2:
The oxygen sensor voltage signal which is processed and calendered by the Engine Control Module (ECM) will be displayed.
1.5 volts in display corresponds to Lambda 1.
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If specified value is not obtained:

- Check oxygen sensor wiring.
If specified value is obtained:

- Replace Heated Oxygen Sensor (HO2S)-G39-
.

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 6-pin harness connector (black) -2- to Heated Oxygen
Sensor (HO2S) -G39- before catalytic converter.
- Connect VAG1598/31 test box at wiring harness to Engine Control
Module (ECM), do not connect ECM Page 24
-19
.
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Electrical Wiring Diagrams, Troubleshooting & Component Locations
If wire connection is OK: - Check the following wire connections for open circuit.Harness connector
Terminal
VAG1598/31 test box
Socket
1 70
2 71
5 51
6 52
- Repair open circuit if necessary.- Check wires to each other for short circuit.
- Replace Engine Control Module (ECM) Page 24
-22
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Test sequence

- Connect VAS5051 tester Page 01
-7 and
select vehicle system "01 - Engine electronics".
Engine must run at idle for this.

Display on VAS5051:
- In selection -1-, click on the diagnostic function "04 - Basic setting".
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Display on VAS5051:
1 - Enter display group Max. input value = 255
- Select function "034" in button field -2- for "display group number 034"
and press Q button to confirm input.
- Use VAG1788/10 RPM adjuster to adjust engine speed to between
2300 and 2800 RPM.

Display on VAS5051:
Note:
This process can take a few minutes. - 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
---
Indicated Engine speed
(RPM) Exhaust
temperature Dynamic factor Diagnostic condition
Functional
range

Test OFF
Test ON
B1-S2 OK
B1-S2 not OK
Specified value 2300 to 2800 RPM
larger than 350 C
0.5 to 2.5 B1-S2 OK
Note


If specified value is not obtained Continuation, Page
24
-88

Note for display field 2:
Calculated value from engine speed and engine load.
Note for display fields 3 and 4:
The dynamic factor is a characteristic for oxygen sensor aging. The smaller the dynamic factor, the further the oxygen sensor
aging process has advanced.
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