1996 AUDI A8 ATQ Engine Oxygen Sensor Control Checking

24-109
Evaluation of display group 037 and 038 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
-111


Open circuit in wire 3 between oxygen sensor
and control module
larger than
1.000 V Short circuit to B+ in wire 4 between oxygen
sensor and control module - Check oxygen sensor wiring and oxygen sensor
behind catalytic converter Page 24
-112

smaller than
0.150 V
Short circuit to Ground (GND) in wire 4 between
oxygen sensor and control module
Pa
ge 41 of 63 Ox
yg
en sensor control, checkin
g
11/23/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU05.24.3

24-110

If specified value in display group 037 and
038 display field 3 or 4 is not obtained:

- Search for leaking air at exhaust system or
catalytic converter (check screw clamps and
exhaust system for damage).

- Check if possibly the oxygen sensors behind
catalytic converter of cylinder bank 1 and 2 have
been switched, in case of extremely different
values (e.g. +500 ms, - 500 ms) of display fields
3 (oxygen sensor correction value) in the
measuring value blocks 037 and 038.
If none of the listed causes applies:

- Replace respective oxygen sensor -before-
catalytic converter
Pa
ge 42 of 63 Ox
yg
en sensor control, checkin
g
11/23/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU05.24.3

24-111

Checking primary voltage
Component location of harness connectors
Overview of component locations - page Page
24
-5

- Disconnect 4-pin harness connector leading to
respective oxygen sensor.

If specified value is not obtained:
If specified value is obtained: - Connect multimeter between terminal 3 and 4 for voltage
measurement.
- Switch ignition on.

Specification: 0.400 to 0.500 V
- Switch ignition off.
- Check oxygen sensor wires Bank 1 page Page 24
-112
or bank 2
page Page 24
-114
.
- Replace appropriate oxygen sensor behind catalytic converter.
Pa
ge 43 of 63 Ox
yg
en sensor control, checkin
g
11/23/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU05.24.3

24-112

Testing Oxygen Sensor Wires
Component location of harness connectors
Overview of component locations, page Page
24
-5

- Disconnect green 4-pin harness connector 1 to
Oxygen Sensor (O2S) Behind Three Way
Catalytic Converter (TWC) -G130-.

- Connect VAG1598/31 test box at wiring harness
to ECM, do not connect ECM Page 24
-17
.

- 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.Harness connector
Terminal
VAG1598/31 test box
Socket
4 68
Pa
ge 44 of 63 Ox
yg
en sensor control, checkin
g
11/23/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU05.24.3

24-113


If no malfunctions are found in wires: - Check shielded wire for short circuit to sensor wires.Harness connector
Terminal
VAG1598/31 test box
Socket
3 32
4 32
- Replace Engine Control Module (ECM) Page 24
-21
.
Pa
ge 45 of 63 Ox
yg
en sensor control, checkin
g
11/23/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU05.24.3

24-114

Check oxygen sensor wires for Oxygen
Sensor (O2S) 2 Behind Three Way Catalytic
Converter (TWC) -G131-.
Component location of harness connectors
Overview of component locations, page Page
24
-5

- Disconnect brown 4-pin harness connector 2 to
Oxygen Sensor (O2S) 2 Behind Three Way
Catalytic Converter (TWC) -G131-.

- Connect VAG1598/31 test box at wiring harness
to ECM, do not connect ECM Page 24
-17
.

- Check the following wire connections for open circuit.Harness connector
Terminal
VAG1598/31 test box
Socket
3 10
4 11
- Repair open circuit if necessary.
- Check wires to each other for short circuit.Harness connector
Terminal
VAG1598/31 test box
Socket
Pa
ge 46 of 63 Ox
yg
en sensor control, checkin
g
11/23/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU05.24.3

4 10
Pa
ge 47 of 63 Ox
yg
en sensor control, checkin
g
11/23/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU05.24.3

24-115


If no malfunctions are found in wires: - Check shielded wire for short circuit to sensor wires.Harness connector
Terminal
VAG1598/31 test box
Socket
3 32
4 32
- Replace Engine Control Module (ECM) Page 24
-21
.
Pa
ge 48 of 63 Ox
yg
en sensor control, checkin
g
11/23/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU05.24.3