AUDI A4 1998 B5 / 1.G AWM Engine Oxygen Sensor Control Checking Service Manual

- Replace Oxygen Sensor (O2S) behind Three Way Catalytic Converter
(TWC) -G130-.
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If specified value is obtained:

- Check voltage supply of oxygen sensor
heating.

Checking voltage supply for oxygen sensor
heating

Note:
When the Engine Control Module (ECM) switches oxygen sensor heating
on and off, it may be observed via the function "read measuring value
block", in display group number 041 display field 4.
If there is no voltage: - Connect multimeter between terminal 1 (B+) and 2 (Ground -GND-) for
voltage measurement.
- Start engine.

Specification: approx. battery voltage

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


Specification: approx. battery voltage
If there is no voltage again:

- Check wire connection from terminal 1 of
connector to Fuel Pump (FP) relay via fuse for
open circuit:

Electrical Wiring Diagrams, Troubleshooting &
Component Locations
If voltage supply is OK:

- Connect multimeter for voltage measurement as follows:Harness connector
Terminal
Measure
to
2 (Ground -GND- activation of Engine Control Module -
ECM-) B+
- Start engine.

Specification: approx. battery voltage, possibly fluctuating
- Switch ignition off.
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If there is no voltage:

- Connect VAG1598/31 test box at wiring harness
to Engine Control Module (ECM), do not connect
ECM Page 24
-19
.

If wire connection is OK, but there is no Ground (GND) supply for oxygen
sensor heating: - Check the following wire connection for open circuit:Harness connector
Terminal
VAG1598/31 test box
Socket
2 63
- Repair open circuit if necessary.
- Replace Engine Control Module (ECM) Page 24
-22
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Oxygen sensor, removing and installing


Special tools and equipment

Procedure
3337 wrench, 7-piece set Locking compound G 052 112 A3

Note:
Coolant reservoir screws must be removed and coolant reservoir must be
placed to side in order to access harness connectors. The coolant hoses
can remain connected. - Disconnect oxygen sensor harness connector and lay to side.
1 - (brown) for Oxygen Sensor (O2S) behind Three Way Catalytic
Converter (TWC) -G130-
2 - (black) for Heated Oxygen Sensor (HO2S) -G39- before catalytic
converter
- Unscrew oxygen sensor using special tool 3337.
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Note the following when installing:

Notes:

Oxygen sensor threads are coated with an
assembly paste. This paste must not contact
sensor openings.
Tightening torque: 55 Nm
Cable of oxygen sensor must always be
secured in the same position when installing so
that contact with the exhaust pipe is avoided.
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