1996 AUDI A4 heating

24-118


Display fields

1 2 3 4
Display group 041: Oxygen sensor heating (bank 1) at idle
Display
xxx kOhm ---
xxx kOhm ---
Indicated
Bank 1, sensor 1 Condition of heating
Bank 2, sensor 1 Condition of heating
Functional range Htng. bef. cat. ON
Htng. bef. cat. OFF Htng. beh. cat. ON
Htng. beh. cat. OFF
Specified value
0 to 0.9 kOhm Htng. bef. cat. ON/OFF
0 to 0.9 kOhm Htng. beh. cat. ON/OFF Important notes to display fields 1, 2, 3 and 4:

If oxygen sensors have not yet reached their operating temperature, there will be no indication in display fields 1 and 3,
i.e. they will both be empty. (increase engine speed to obtain specified values).
After reaching operating temperature of the two oxygen sensors, a resistance of less than 0.9 kOhm must be indicated in
display fields 1 and 3.
Do not continue test until a resistance of less than 0.9 kOhm is indicated in display fields 1 and 3.
At certain points of operation, the ECM "pulses" oxygen sensor heating. This means that oxygen sensor heating is
switched on and off at these points. It is entirely possible that the specified value "Htng. bef. Cat. OFF" or "Htng. beh. Cat.
OFF" will appear in display fields 2 and 4

- Press -C- button.
Pa
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11/23/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
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pair&id=AUDI.B5.FU05.24.3

24-119

Read Measuring Value Block 42
1
2
3
4

When indicated on display:
- Check specified values in display fields 1 and 3.

Display fields

1 2 3 4
Display group 042: Oxygen sensor heating (bank 2) at idle
Display
xxx kOhm ---
xxx kOhm ---
Indicated
Bank 2, sensor 1 Condition of heating
Bank 2, sensor 2 Condition of heating
Functional range Htng. bef. cat. ON
Htng. bef. cat. OFF Htng. beh. cat. ON
Htng. beh. cat. OFF
Specified value
0 to 0.9 kOhm Htng. bef. cat. ON/OFF
0 to 0.9 kOhm Htng. beh. cat. ON/OFF Important notes to display fields 1, 2, 3 and 4:

If oxygen sensors have not yet reached their operating temperature, there will be no indication in display fields 1 and 3,
i.e. they will both be empty. (increase engine speed to obtain specified values).
After reaching operating temperature of the two oxygen sensors, a resistance of less than 0.9 kOhm must be indicated in
display fields 1 and 3.
Do not continue test until a resistance of less than 0.9 kOhm is indicated in display fields 1 and 3.
At certain points of operation, the ECM "pulses" oxygen sensor heating. This means that oxygen sensor heating is
switched on and off at these points. It is entirely possible that the specified value "Htng. bef. Cat. OFF" or "Htng. beh. Cat.
Pa
ge 53 of 63 Ox
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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

24-120
If specified value is not obtained:

- Check voltage supply of oxygen sensor heating
Page 24
-121
.

- Check oxygen sensor signal wire and activation
Page 24
-112
or Page 24
-114
.
Pa
ge 55 of 63 Ox
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11/23/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
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e=re
pair&id=AUDI.B5.FU05.24.3

24-121

Checking voltage supply for oxygen sensor
heating

Test requirement:

Fuse for oxygen sensor heating OK

Electrical Wiring Diagrams, Troubleshooting &
Component Locations binder

Fuel Pump (FP) OK, checking Page 24
-
49
.
Component location of harness connectors
Overview of component locations, page Page
24
-5

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

- Connect multimeter between terminal 1 and 2 for voltage
measurement.
Pa
ge 56 of 63 Ox
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11/23/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
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yp
e=re
pair&id=AUDI.B5.FU05.24.3

24-122

- Start engine.


Specification: approx. battery voltage,
possibly fluctuating

Notes:

At certain operating points, the ECM "pulses"
the Ground (GND) for oxygen sensor heating.
This means that the Ground (GND) is
constantly switched on and off at these points.
It is therefore possible that the voltage
displayed on the tester will fluctuate.
It is possible to observe the ECM switching
oxygen sensor heating on and off within the
function "read measuring value block", display
group numbers 041 and 042.
If there is no voltage:

- Connect multimeter for voltage measurement as follows:Harness connector
Terminal
Measure to
1 (B+) Vehicle Ground (GND)
- Operate starter briefly.
Pa
ge 57 of 63 Ox
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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