AUDI A4 1998 B5 / 1.G AWM Engine Oxygen Sensor Control Checking User Guide

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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 6-pin harness connector (black) -2- to Heated Oxygen
Sensor (HO2S) -G39- before catalytic converter.

- Connect multimeter between terminal 1 and 5 for voltage
measurement.
- Switch ignition on.

Specification: 0.400 to 0.500 V
- Switch ignition off.
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If specified value is not obtained:

- Check oxygen sensor wiring.
If specified value is obtained:

- Replace Heated Oxygen Sensor (HO2S)-G39-
.

Checking oxygen sensor wires

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 6-pin harness connector (black) -2- to Heated Oxygen
Sensor (HO2S) -G39- before catalytic converter.
- Connect VAG1598/31 test box at wiring harness to Engine Control
Module (ECM), do not connect ECM Page 24
-19
.
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Electrical Wiring Diagrams, Troubleshooting & Component Locations
If wire connection is OK: - Check the following wire connections for open circuit.Harness connector
Terminal
VAG1598/31 test box
Socket
1 70
2 71
5 51
6 52
- Repair open circuit if necessary.- Check wires to each other for short circuit.
- Replace Engine Control Module (ECM) Page 24
-22
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Oxygen sensor aging, oxygen sensor
before catalytic converter, checking


Special Tools and Equipment

VAG1788/10 RPM adjuster

Test requirement:
VAS5051 with VAG5051/1Coolant Temperature at least 80 C.
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Test sequence

- Connect VAS5051 tester Page 01
-7 and
select vehicle system "01 - Engine electronics".
Engine must run at idle for this.

Display on VAS5051:
- In selection -1-, click on the diagnostic function "04 - Basic setting".
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Display on VAS5051:
1 - Enter display group Max. input value = 255
- Select function "034" in button field -2- for "display group number 034"
and press Q button to confirm input.
- Use VAG1788/10 RPM adjuster to adjust engine speed to between
2300 and 2800 RPM.

Display on VAS5051:
Note:
This process can take a few minutes. - Check specified value in display field -4-.
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Display fields

1 2 3 4
Display group 034: Diagnostic oxygen sensor aging
Display xxxx/min
xxx C
x.x
---
Indicated Engine speed
(RPM) Exhaust
temperature Dynamic factor Diagnostic condition
Functional
range

Test OFF
Test ON
B1-S2 OK
B1-S2 not OK
Specified value 2300 to 2800 RPM
larger than 350 C
0.5 to 2.5 B1-S2 OK
Note


If specified value is not obtained Continuation, Page
24
-88

Note for display field 2:
Calculated value from engine speed and engine load.
Note for display fields 3 and 4:
The dynamic factor is a characteristic for oxygen sensor aging. The smaller the dynamic factor, the further the oxygen sensor
aging process has advanced.
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Continuation
If specified value in display field 3 and 4 is not
obtained:

- Road test vehicle in order to free oxygen sensor
of possible residue and repeat test.
If specified value in display field 3 and 4 is not
obtained, even after road test:

- Replace Heated Oxygen Sensor (HO2S)-G39-
.
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Oxygen sensor heating, Oxygen Sensor
(O2S) Heater -Z19- before catalytic
converter, checking

Special Tools and Equipment

VAG1526A
VAG1594A
VAG1598/31
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Test requirements:

Coolant Temperature at least 80 C.

Fuse for oxygen sensor heating OK

Electrical Wiring Diagrams, Troubleshooting &
Component Locations

Test sequence

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 6-pin harness connector (black) -2- to Heated Oxygen
Sensor (HO2S) -G39- before catalytic converter.

If specified value is not obtained: - Connect multimeter between terminal 3 and 4 for resistance
measurement.

Specified value at room temperature: 2.5 to 10
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