heating AUDI A4 1998 B5 / 1.G ATQ Engine Oxygen Sensor Control Checking

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
.
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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
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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