ignition AUDI A4 1999 B5 / 1.G ATW Engine Oxygen Sensor Control Workshop Manual
Page 11 of 37
24-81
If specified value is not obtained:
If specified value is obtained:
Checking oxygen sensor wires - Connect multimeter between terminal 3 and 4 for voltage
measurement.
- Switch ignition on.
Specification: 0.400 to 0.500 V
- Switch ignition off.
- Check oxygen sensor wiring.
- Replace Heated Oxygen Sensor (HO2S) -G39-.
Note:
Coolant reservoir screws must be removed and coolant reservoir must be
placed to side in order to access the harness connector. The coolant
hoses can remain connected. - Disconnect 4-pin harness connector -2- (black) to Heated Oxygen
Sensor (HO2S) -G39- before catalytic converter.
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Page 26 of 37
24-96
Checking primary voltage
Note:
Coolant reservoir screws must be removed and coolant reservoir must be
placed to side in order to access the harness connector. The coolant
hoses can remain connected. - Disconnect 4-pin harness connector -1- (brown) to Oxygen Sensor
(O2S) behind Three Way Catalytic Converter (TWC) -G130-.
If specified value is not obtained:
If specified value is obtained: - Connect multimeter between terminal 3 and 4 for voltage
measurement.
- Switch ignition on.
Specification: 0.400 to 0.500 V
- Switch ignition off.
- Check oxygen sensor wiring.
- Replace Oxygen Sensor (O2S) behind Three Way Catalytic Converter
(TWC) -G130-.
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Page 34 of 37
24-103
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:
If there is no voltage: - 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.
- Connect VAG1598/31 test box at wiring harness to Engine Control
Module (ECM), do not connect ECM Page 24
-19
.
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