1996 AUDI A4 wiring

24-82
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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p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU07.24.2

24-83


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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play?action=Goto&t
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pair&id=AUDI.B5.FU07.24.2

24-90

Test requirements:

Coolant Temperature at least 80 C.

Fuse for oxygen sensor heating OK

Electrical Wiring Diagrams, Troubleshooting &
Component Locations

Test sequence

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.

If specified value is not obtained: - Connect multimeter between terminal 3 and 4 for resistance
measurement.

Specified value at room temperature: 2.5 to 10
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11/22/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
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pair&id=AUDI.B5.FU07.24.2

24-92

- Operate starter briefly.


Specification: approx. battery voltage
If there is no voltage again:

- Check wire connection from terminal 3 of
connector to Fuel Pump (FP) relay via fuse for
open circuit:

Electrical Wiring Diagrams, Troubleshooting &
Component Locations
If voltage supply is OK:

Note: - Connect multimeter for voltage measurement as follows:Harness connector
Terminal
Measure
to
4 (Ground -GND- activation of Engine Control Module -
ECM-) B+
- Start engine.

Specification: approx. battery voltage
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11/22/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
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pair&id=AUDI.B5.FU07.24.2

24-93

- Switch ignition off.
If there is no voltage:

- Connect VAG1598/31 test box at wiring harness
to Engine Control Module (ECM), do not connect
ECM Page 24
-19
.

Electrical Wiring Diagrams, Troubleshooting & Component Locations
If wire connection is OK, but there is no Ground (GND) supply for oxygen
sensor heating: - Check the following wire connection for open circuit:Harness connector
Terminal
VAG1598/31 test box
Socket
4 5
- Repair open circuit if necessary.- Replace Engine Control Module (ECM) Page 24
-22
Pa
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en sensor control, checkin
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11/22/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU07.24.2

24-102
Evaluation display group 037 Display field: 2
Possible cause
Corrective action
constant about
0.450 V
Open circuit in wire 4 between oxygen sensor
and control module - Check primary voltage Page 24
-104


Open circuit in wire 3 between oxygen sensor
and control module
larger than
0.950 V Short circuit to B+ in wire 4 between oxygen
sensor and control module - Check oxygen sensor wiring, oxygen sensor after
catalytic converter Page 24
-105

smaller than
0.100 V
Short circuit to Ground (GND) in wire 4 between
oxygen sensor and control module
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11/22/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
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e=re
pair&id=AUDI.B5.FU07.24.2

24-105
If specified value is not obtained:

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

- Replace Oxygen Sensor (O2S) behind Three
Way Catalytic Converter (TWC) -G130-.

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
.
Pa
ge 37 of 46 Ox
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en sensor control, checkin
g
11/22/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU07.24.2

24-106


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
3 68
4 69
- Repair open circuit if necessary.- Check wires to each other for short circuit.
- Replace Engine Control Module (ECM) Page 24
-22
Pa
ge 38 of 46 Ox
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en sensor control, checkin
g
11/22/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU07.24.2