AUDI A4 1999 B5 / 1.G AFC Engine Heated Oxygen Sensor After Converter Checking Workshop Manual

24-53


Heated Oxygen Sensor
(HO2S) after Three Way
Catalytic Converter (TWC),
checking

Notes:

G130 = O2S behind three way catalytic
converter, bank 1
G131 = O2S behind three way catalytic
converter, bank 2
For functional check of O2S behind three way
catalytic converter -G130- or -G131- Repair
Group 01, Read measuring value block, display
group 041

- Disconnect connector for O2S behind three way
catalytic converter -G130- or- G131- (component
locations page 24
-1 ).

If there is continuity: - Using multimeter (Fluke 83 or equivalent) set for measuring resistance
( ), check for continuity (short circuit) between oxygen sensor
terminals 3 (GND wire) and 4 (signal wire).
Pa
ge 1 of 7 Heated Ox
yg
en Sensor
(HO2S
) after Three Wa
y Catal
ytic Converter
(TWC
), 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.FU01.24.13

If the wiring is OK (no continuity): - Replace heated oxygen sensor.

- Switch multimeter (Fluke 83 or equivalent) to measure voltage (2 volt
range) and connect between harness connector terminals 3 (GND) and
4 (signal wire).
Pa
ge 2 of 7 Heated Ox
yg
en Sensor
(HO2S
) after Three Wa
y Catal
ytic Converter
(TWC
), 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.FU01.24.13

24-54

- Switch ignition ON.


Specified value: 400 50 mV If the specified value is not obtained, check
wiring to ECM as follows:

- Switch ignition OFF.

- Connect VAG 1598/19 test box to ECM wiring
harness page 01
-255
.

- Check following wiring connections for
continuity.


Specified value: max. 1
Heated
oxygen
sensor Connector
terminal VAG 1598/19 test
box socket
number
-G130- 3
4 C17
C20
-G131- 3
4 C17
C21
Pa
ge 3 of 7 Heated Ox
yg
en Sensor
(HO2S
) after Three Wa
y Catal
ytic Converter
(TWC
), 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.FU01.24.13

If the specified value is not obtained:

If wiring OK: - Eliminate open or short circuit using wiring diagram.
- Replace ECM page 01
-265
.
Pa
ge 4 of 7 Heated Ox
yg
en Sensor
(HO2S
) after Three Wa
y Catal
ytic Converter
(TWC
), 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.FU01.24.13

24-55

Oxygen sensor heater, checking

Notes:

Z29 = Oxygen Sensor (O2S) heater, bank 1
Z30 = Oxygen Sensor (O2S) heater, bank 2
For functional check of O2S heater -Z29- or -
Z30- Repair Group 01, Read measuring
value block, display group 040

- Disconnect heated oxygen sensor harness
connector (component locations page 24
-1 )

If the specified value is not obtained: - Switch multimeter (Fluke 83 or equivalent) to 20 volt range and connect
between terminals 1 (B+) and 2 (GND).
- Start engine and let idle.
Specified value: approx. 12 to 14 V
- Check oxygen sensor heater fuse.
- Check fuel pump relay page 24
-24
.

- Check wiring for continuity between terminal 1 and fuse in fuse holder
using wiring diagram, if necessary check terminal assignments.
Pa
ge 5 of 7 Heated Ox
yg
en Sensor
(HO2S
) after Three Wa
y Catal
ytic Converter
(TWC
), 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.FU01.24.13

Specified value: max. 1
Pa
ge 6 of 7 Heated Ox
yg
en Sensor
(HO2S
) after Three Wa
y Catal
ytic Converter
(TWC
), 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.FU01.24.13

24-56

- Check wiring for continuity between terminals 2
and 8 on ECM connector E.


Specified value: max. 1
- Check wiring for continuity between terminals 2
and 3 of ECM connector E (O2S heater -Z30-).


Specified value: max. 1 If the specified value is obtained:

Note:
With small increases in temperature, resistance will increase sharply.
If the specified value is not obtained: -
Switch multimeter (Fluke 83 or equivalent) to measure resistance ( )
and connect between terminals 1 and 2.
Specified value (room temperature): approx. 2 to 5 - Replace heated oxygen sensor.
Pa
ge 7 of 7 Heated Ox
yg
en Sensor
(HO2S
) after Three Wa
y Catal
ytic Converter
(TWC
), 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.FU01.24.13