1996 AUDI A4 ESP

24-29

Checking HO2S reference voltage (Banks 1,
2)

- Disconnect 4-pin connector for respective
HO2S.

If voltage is NOT OK:
If voltage is OK: - Connect multimeter US1119 (Fluke 83 or equivalent) between harness
connector terminals 3 and 4 (to ECM), using adapter cables from
VW1594 connector test kit.
- Start engine and measure voltage.
Specified value: 0.40-0.50 volts
- Switch ignition off.
- Check HO2S wiring.

Bank 1, sensor 1 page 24
-30
.

Bank 2, sensor 1 page 24
-32
.
- Replace respective Heated Oxygen Sensor (HO2S).
Pa
ge 39 of 166 Motronic Multi
port Fuel In
jection
(MFI
) and i
gnition s
ystem
11/23/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU03.24.1

24-37

Continuation

- Disconnect 4-pin connector (black) for
respective Heated Oxygen Sensor (HO2S).

If resistance is NOT OK: - Connect multimeter US1119 (Fluke 83 or equivalent) between HO2S
connector terminals 1 and 2, using VW1594 connector test kit.
- Measure resistance.

Specified value: 0.0-19.9 - Replace respective Heated Oxygen Sensor (HO2S).
Pa
ge 49 of 166 Motronic Multi
port Fuel In
jection
(MFI
) and i
gnition s
ystem
11/23/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU03.24.1

24-47

Checking O2S reference voltage

- Disconnect 4-pin connector for respective
Oxygen Sensor (O2S) behind Three Way
Catalytic Converter (TWC).

If voltage is NOT OK:
If voltage is OK: - Connect multimeter US1119 (Fluke 83 or equivalent) between harness
connector terminals 3 and 4 (to ECM), using adapter cables from
VW1594 connector test kit.
- Start engine and measure voltage.
Specified value: 0.40 to 0.50 volts
- Switch ignition off.
- Check O2S wiring.

Bank 1, sensor 2 page 24
-48
.

Bank 2, sensor 2 page 24
-50
.
- Replace respective O2S behind TWC.
Pa
ge 60 of 166 Motronic Multi
port Fuel In
jection
(MFI
) and i
gnition s
ystem
11/23/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU03.24.1

24-55

Continuation

- Disconnect 4-pin connector for respective
Oxygen Sensor (O2S) behind Three Way
Catalytic Converter (TWC).

If resistance is NOT OK:
If resistance is OK: - Connect multimeter US1119 (Fluke 83 or equivalent) between HO2S
connector terminals 1 and 2, using VW1594 connector test kit.
- Measure resistance.

Specified value: 0.00-19.9 - Replace respective Oxygen Sensor (O2S) behind TWC.
- Switch multimeter to 20 VDC measuring range.
Pa
ge 70 of 166 Motronic Multi
port Fuel In
jection
(MFI
) and i
gnition s
ystem
11/23/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU03.24.1

24-96
If the fuel pump does not respond:

- Check fuel pump relay actuation page 24
-
99
.
If the LED test light does not light up:

- Repeat test at other terminal of fuse 28.

If the LED light still does not light up:
- Check wiring for open or short circuits between fuse 28 and terminal 30
at relay position 6, using the applicable wiring diagram. Repair wiring
as necessary.

Specified value: max. 1.5

Note:
This step lets the fuel pump run without the engine running. The closed
throttle position switch must be closed during the test, or the selected fuel
injector will discharge fuel when it is actuated 5 times. - Connect VAG1527B LED voltage tester between Ground and one of
the two terminals for fuse 29.
Pa
ge 122 of 166 Motronic Multi
port Fuel In
jection
(MFI
) and i
gnition s
ystem
11/23/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU03.24.1