AUDI A6 1995 C5 / 2.G ATQ Engine Oxygen Sensor Control Checking
Manufacturer: AUDI, Model Year: 1995, Model line: A6, Model: AUDI A6 1995 C5 / 2.GPages: 63, PDF Size: 0.31 MB
Page 51 of 63
24-118
Display fields
1 2 3 4
Display group 041: Oxygen sensor heating (bank 1) at idle
Display
xxx kOhm ---
xxx kOhm ---
Indicated
Bank 1, sensor 1 Condition of heating
Bank 2, sensor 1 Condition of heating
Functional range Htng. bef. cat. ON
Htng. bef. cat. OFF Htng. beh. cat. ON
Htng. beh. cat. OFF
Specified value
0 to 0.9 kOhm Htng. bef. cat. ON/OFF
0 to 0.9 kOhm Htng. beh. cat. ON/OFF Important notes to display fields 1, 2, 3 and 4:
If oxygen sensors have not yet reached their operating temperature, there will be no indication in display fields 1 and 3,
i.e. they will both be empty. (increase engine speed to obtain specified values).
After reaching operating temperature of the two oxygen sensors, a resistance of less than 0.9 kOhm must be indicated in
display fields 1 and 3.
Do not continue test until a resistance of less than 0.9 kOhm is indicated in display fields 1 and 3.
At certain points of operation, the ECM "pulses" oxygen sensor heating. This means that oxygen sensor heating is
switched on and off at these points. It is entirely possible that the specified value "Htng. bef. Cat. OFF" or "Htng. beh. Cat.
OFF" will appear in display fields 2 and 4
- Press -C- button.
Pa
ge 51 of 63 Ox
yg
en sensor control, checkin
g
11/23/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU05.24.3
Page 52 of 63
Read Measurin
g Value Block
Q
Input display group number XXX
When indicated on display:
- Press buttons -0-, -4- and -2- to select "display group number 042" and press -Q-
button to confirm input.
Pa
ge 52 of 63 Ox
yg
en sensor control, checkin
g
11/23/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU05.24.3
Page 53 of 63
24-119
Read Measuring Value Block 42
1
2
3
4
When indicated on display:
- Check specified values in display fields 1 and 3.
Display fields
1 2 3 4
Display group 042: Oxygen sensor heating (bank 2) at idle
Display
xxx kOhm ---
xxx kOhm ---
Indicated
Bank 2, sensor 1 Condition of heating
Bank 2, sensor 2 Condition of heating
Functional range Htng. bef. cat. ON
Htng. bef. cat. OFF Htng. beh. cat. ON
Htng. beh. cat. OFF
Specified value
0 to 0.9 kOhm Htng. bef. cat. ON/OFF
0 to 0.9 kOhm Htng. beh. cat. ON/OFF Important notes to display fields 1, 2, 3 and 4:
If oxygen sensors have not yet reached their operating temperature, there will be no indication in display fields 1 and 3,
i.e. they will both be empty. (increase engine speed to obtain specified values).
After reaching operating temperature of the two oxygen sensors, a resistance of less than 0.9 kOhm must be indicated in
display fields 1 and 3.
Do not continue test until a resistance of less than 0.9 kOhm is indicated in display fields 1 and 3.
At certain points of operation, the ECM "pulses" oxygen sensor heating. This means that oxygen sensor heating is
switched on and off at these points. It is entirely possible that the specified value "Htng. bef. Cat. OFF" or "Htng. beh. Cat.
Pa
ge 53 of 63 Ox
yg
en sensor control, checkin
g
11/23/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU05.24.3
Page 54 of 63
OFF" will appear in display fields 2 and 4
Pa
ge 54 of 63 Ox
yg
en sensor control, checkin
g
11/23/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU05.24.3
Page 55 of 63
24-120
If specified value is not obtained:
- Check voltage supply of oxygen sensor heating
Page 24
-121
.
- Check oxygen sensor signal wire and activation
Page 24
-112
or Page 24
-114
.
Pa
ge 55 of 63 Ox
yg
en sensor control, checkin
g
11/23/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU05.24.3
Page 56 of 63
24-121
Checking voltage supply for oxygen sensor
heating
Test requirement:
Fuse for oxygen sensor heating OK
Electrical Wiring Diagrams, Troubleshooting &
Component Locations binder
Fuel Pump (FP) OK, checking Page 24
-
49
.
Component location of harness connectors
Overview of component locations, page Page
24
-5
- Disconnect 4-pin harness connector leading to
respective oxygen sensor.
- Connect multimeter between terminal 1 and 2 for voltage
measurement.
Pa
ge 56 of 63 Ox
yg
en sensor control, checkin
g
11/23/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU05.24.3
Page 57 of 63
24-122
- Start engine.
Specification: approx. battery voltage,
possibly fluctuating
Notes:
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.
It is possible to observe the ECM switching
oxygen sensor heating on and off within the
function "read measuring value block", display
group numbers 041 and 042.
If there is no voltage:
- Connect multimeter for voltage measurement as follows:Harness connector
Terminal
Measure to
1 (B+) Vehicle Ground (GND)
- Operate starter briefly.
Pa
ge 57 of 63 Ox
yg
en sensor control, checkin
g
11/23/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU05.24.3
Page 58 of 63
Specification: approx. battery voltage
Pa
ge 58 of 63 Ox
yg
en sensor control, checkin
g
11/23/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU05.24.3
Page 59 of 63
24-123
If there is no voltage again:
- Check wire connection from terminal 1 to Fuel
Pump (FP) relay via fuse for open circuit.
Electrical Wiring Diagrams, Troubleshooting &
Component Locations binder 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 ECM, do not
connect ECM Page 24
-17
.
Pa
ge 59 of 63 Ox
yg
en sensor control, checkin
g
11/23/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU05.24.3
Page 60 of 63
24-124
- Check the following wire connection for open circuit:
Oxygen Sensor (O2S) heater -Z19- bank 1 before catalytic converter:
Harness connector
Terminal
VAG1598/31 test box
Socket
2 5
Oxygen Sensor (O2S) heater -Z28- bank 2 before catalytic converter:
Harness connector
Terminal
VAG1598/31 test box
Socket
2 4
Oxygen Sensor (O2S) heater -Z29- bank 1 behind catalytic converter:
Harness connector
Terminal
VAG1598/31 test box
Socket
2 63
Oxygen Sensor (O2S) heater -Z30- bank 2 behind catalytic converter:
Harness connector
Terminal
VAG1598/31 test box
Socket
2 6
Pa
ge 60 of 63 Ox
yg
en sensor control, checkin
g
11/23/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU05.24.3