lock AUDI A4 1999 B5 / 1.G ATW Engine Oxygen Sensor Control Workshop Manual

24-102

- Start engine.


Specification: approx. battery voltage,
possibly fluctuating

Note:

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.
When the ECM switches oxygen sensor heating
on and off can be observed, if necessary, via
the function "read measuring value block"
display group number 041.
If there is no voltage:

- Connect multimeter for voltage measurement as
follows:

Harness connector
Terminal
Measure to
1 (B+) Vehicle Ground (GND)
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24-105

Oxygen sensor, removing and installing


Special tools and equipment

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

Procedure

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 4-pin harness connector of oxygen sensor and lay it 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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