AUDI A4 1998 B5 / 1.G AWM Engine Oxygen Sensor Control Checking Owner's Guide

24-99


Display on VAS5051:
Checking oxygen sensor control after catalytic converter
Test requirement: - Do not continue test until indication in display field -2- has reached
"110" at least once.
Engine continues to run at 2600 RPM.
-
Click on - button

Display on VAS5051:
1 - Enter display group Max. input value = 255
- Select function "037" in button field -2- for "display group number 037"
and press -Q- button to confirm input.
Pa
ge 31 of 46 Ox
yg
en sensor control, checkin
g
11/22/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU07.24.2

24-100


Display on VAS5051:
- Check oxygen sensor voltage in display field -2-.
- Check oxygen sensor correction value in display field -3- and
diagnostic result in display field -4-.
Pa
ge 32 of 46 Ox
yg
en sensor control, checkin
g
11/22/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU07.24.2

24-101


Display fields

1 2 3 4
Display group 037: Diagnostic oxygen sensor control system
Display xxx %
x.xxx V
x.xx
---
Indicated Engine
load Oxygen sensor voltage
Bank 2, sensor 1 Oxygen sensor correction value
between bank 1, sensor 1 and
bank 1, sensor 2 Diagnostic condition
Functional
range


Test OFF
Test ON
System OK
System not OK
Specified
value 13 to 40
% 0.100 to 0.950 volts
smaller than 0.02 System OK
Note

If specified value is not
obtained: Evaluation
Page 24
-102


If "System not OK" is
displayed: Check DTC
memory Page 01
-12

Note for display field 2:
Oxygen sensor voltage bank 1, sensor 2 should remain fairly constant. Strong voltage fluctuations point to a damaged
catalytic converter.
Pa
ge 33 of 46 Ox
yg
en sensor control, checkin
g
11/22/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU07.24.2

24-102
Evaluation display group 037 Display field: 2
Possible cause
Corrective action
constant about
0.450 V
Open circuit in wire 4 between oxygen sensor
and control module - Check primary voltage Page 24
-104


Open circuit in wire 3 between oxygen sensor
and control module
larger than
0.950 V Short circuit to B+ in wire 4 between oxygen
sensor and control module - Check oxygen sensor wiring, oxygen sensor after
catalytic converter Page 24
-105

smaller than
0.100 V
Short circuit to Ground (GND) in wire 4 between
oxygen sensor and control module
Pa
ge 34 of 46 Ox
yg
en sensor control, checkin
g
11/22/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU07.24.2

24-103

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-.

Note:
If oxygen sensor voltage is OK and oxygen
sensor correction value is still above 0.02 ms,
even after a road test, this suggests aging of an
oxygen sensor before catalytic converter.
Pa
ge 35 of 46 Ox
yg
en sensor control, checkin
g
11/22/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU07.24.2

24-104

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-.

- Connect multimeter between terminal 3 and 4 for voltage
measurement.
- Switch ignition on.

Specification: 0.400 to 0.500 V
- Switch ignition off.
Pa
ge 36 of 46 Ox
yg
en sensor control, checkin
g
11/22/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU07.24.2

24-105
If specified value is not obtained:

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

- Replace Oxygen Sensor (O2S) behind Three
Way Catalytic Converter (TWC) -G130-.

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 4-pin harness connector -1- (brown) to Oxygen Sensor
(O2S) behind Three Way Catalytic Converter (TWC) -G130-.
- Connect VAG1598/31 test box at wiring harness to Engine Control
Module (ECM), do not connect ECM Page 24
-19
.
Pa
ge 37 of 46 Ox
yg
en sensor control, checkin
g
11/22/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU07.24.2

24-106


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
3 68
4 69
- Repair open circuit if necessary.- Check wires to each other for short circuit.
- Replace Engine Control Module (ECM) Page 24
-22
Pa
ge 38 of 46 Ox
yg
en sensor control, checkin
g
11/22/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU07.24.2

24-107


Oxygen sensor heating, Oxygen Sensor
(O2S) Heater 1 -Z29- after catalytic
converter, checking

Special Tools and Equipment

VAG1526A
VAG1594A
VAG1598/31
Pa
ge 39 of 46 Ox
yg
en sensor control, checkin
g
11/22/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU07.24.2

24-108

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 4-pin harness connector -1- (brown) to Oxygen Sensor
(O2S) behind Three Way Catalytic Converter (TWC) -G130-.

If specified value is not obtained: - Connect multimeter between terminal 1 and 2 for resistance
measurement.

Specified value at room temperature: 6.4 to 47.5
Pa
ge 40 of 46 Ox
yg
en sensor control, checkin
g
11/22/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU07.24.2