1995 AUDI A6 sensor

24-14

Fuel injection system, servicing

Servicing ignition system page 28
-1

Notes:

Fuel hoses in the engine compartment must be
secured with spring-type clamps. Screw-type
clamps or equivalent must not be used.
The Engine Control Module (ECM) has On
Board Diagnostic (OBD) capability, and is
equipped with Diagnostic Trouble Code (DTC)
memory. Before repairing or adjusting any
components or systems, first check DTC
memory. Also check all vacuum connections for
leaks ("false air").
For proper operation of electrical and electronic
components, a Battery Positive Voltage (B+)
supply of at least 11.5 volts is required.
Do not use any gasket sealers or other
automotive chemical compounds that contain
silicone. Traces of silicone drawn into the
engine pass unburned into the exhaust and can
damage the oxygen sensors.
Do not use any electrical contact sprays or
equivalent near oxygen sensor connections.
Pa
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Proper oxygen sensor function requires
reference to outside air via the cable. If any
contact spray reaches the oxygen sensor, it can
cause damage or improper function.
During some tests, malfunctions are recognized
by the ECM and stored in DTC memory. For
this reason, always check DTC memory (
page 01
-16
) after all tests and repairs, and
erase DTC memory as necessary.
Pa
ge 19 of 166 Motronic Multi
port Fuel In
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(MFI
) and i
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24-16

Idle speed, checking


Notes:

Idle speed, ignition timing and CO-content
cannot be adjusted.
Idle speed is maintained by the Throttle valve
control module.
CO-content is maintained and adjusted by
Oxygen Sensor (O2S) control. Malfunctions in
O2S control are recognized by On Board
Diagnostic (OBD) and stored in DTC memory.

Required special tools and test equipment
VAG1551 or VAG1552 Scan Tool (ST) with
VAG1551/3 adapter cable
Pa
ge 21 of 166 Motronic Multi
port Fuel In
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(MFI
) and i
gnition s
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11/23/2002 htt
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pair&id=AUDI.B5.FU03.24.1

24-19

- Compare display with specified values (display
fields 1-4):

Display fields

1 2 3 4
Display group 1: Engine idle speed
Display xxxx RPM
xx.x C
xx.x% xx.x %
Indicates Idle speed
(in 40 RPM steps) Engine Coolant
Temperature (ECT) Oxygen Sensor
(O2S) control, Bank
1 Oxygen Sensor
(O2S) control, Bank
2
Range 0 - 6800 RPM
-48.0 - 143.2 C
(-54 - 289 F)
-25.0 to +25.0 % -25.0 to +25.0 %
Specified
value 620 - 740 RPM
(all-wheel drive) 80.0 - 105.0 C
(176 - 221 F) -10.0 to +10.0 %
value must change by
at least 2 % -10.0 to +10.0 %
value must change by
at least 2 %
740 - 860 RPM
(front-wheel drive)

If not as specified Evaluation of
display group 1 page 24
-21

--- If not as specified:
- Check HO2S and O2S control before TWC
page 24
-22

Pa
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port Fuel In
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(MFI
) and i
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11/23/2002 htt
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yp
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24-22

Heated Oxygen Sensor (HO2S) and
Oxygen Sensor (O2S) control before
TWC, checking


Notes:

Connector for Heated Oxygen Sensor (HO2S)
before Three Way Catalytic Converter (TWC) -
G39- (bank 1, sensor 1): 4-pin, black.
Connector for Heated Oxygen Sensor (HO2S) 2
before Three Way Catalytic Converter (TWC) -
G108- (Bank 2, sensor 1): 4-pin, black.
Component location page 24
-1

Required special tools and test equipment

VAG1551 or VAG1552 Scan Tool (ST) with
VAG1551/3 adapter cable
VAG1598/22 test box
Multimeter US1119 (Fluke 83 or equivalent)
VW1594 connector test kit

Pa
ge 28 of 166 Motronic Multi
port Fuel In
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(MFI
) and i
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11/23/2002 htt
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play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU03.24.1

24-24

- Check learning values for Oxygen Sensor (O2S)
control before TWC (display fields 1-4):

Display fields

1 2 3 4
Display group 32: Oxygen Sensor (O2S) control learning values (before TWC)
Display xx.x % xx.x % xx.x % xx.x %
Indicates O2S control learning
value at idle (additive)
(before TWC)
Bank 1, Sensor 1 O2S control learning value at
part load (multiplicative)
(before TWC)
Bank 1, Sensor 1 O2S control learning
value at idle (additive)
(before TWC)
Bank 2, Sensor 1 O2S control learning value at
part load (multiplicative)
(before TWC)
Bank 2, Sensor 1
Range -25.0 to +25.0 % -25.0 to +25.0 % -25.0 to +25.0 % -25.0 to +25.0 %
Specified
value -10.0 to +10.0 %
(can vary slightly) -10.0 to +10.0 %
(can vary slightly) -10.0 to +10.0 %
(can vary slightly) -10.0 to +10.0 %
(can vary slightly)
If not as specified Evaluation of display group 32, page 24
-27

If displayed values are OK (as specified):

- Press -C- button.

- Press buttons -0-, -3- and -3- to input display
group number 33, and press -Q- button to
confirm input.
Pa
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port Fuel In
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(MFI
) and i
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24-25

- Check Oxygen Sensor (O2S) control before
TWC (display fields 1-4):

Display fields

1 2 3 4
Display group 33: Oxygen Sensor (O2S) control (before TWC)
Display xx.x % x.xxx V xx.x % x.xxx V
Indicates O2S control
Bank 1, Sensor 1
(before TWC) O2S voltage
Bank 1, Sensor 1
(before TWC) O2S control
Bank 2, Sensor 1
(before TWC) O2S voltage
Bank 1, Sensor 1
(before TWC)
Range -25.0 to +25.0 % 0.000-1.000 V -25.0 to +25.0 % 0.000-1.000 V
Specified
value -10.0 to +10.0 %
value must change by
at least 2 % 0.000 to 1.000 V
value must fluctuate at least
30 times per minute, and
change by at least 0.3 volts -10.0 to +10.0 %
value must change by
at least 2 % 0.000 to 1.000 V
value must fluctuate at least
30 times per minute, and
change by at least 0.3 volts

If not as specified
page 24
-26
,
Continuation
If not as specified page 24
-
28
, Evaluation of display
group 33
If not as specified
page 24
-26
,
Continuation
If not as specified page 24
-
28
, Evaluation of display
group 33
Pa
ge 33 of 166 Motronic Multi
port Fuel In
jection
(MFI
) and i
gnition s
ystem
11/23/2002 htt
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yp
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pair&id=AUDI.B5.FU03.24.1

24-26

Continuation
If the value in either display field 1 or 3 is NOT
OK, or if the value does not fluctuate by at least 2
%:

- Road test to condition oxygen sensor(s)
(eliminate possible contamination) and repeat
test.
If the value in either display field 1 or 3 is still
NOT OK, or if it still does not fluctuate by at least
2 %:

- Check Oxygen Sensor (O2S) heater(s) page
24
-34
.
If the value in either display field 1 or 3 remains
constant:

- Check oxygen sensor voltage(s) (display fields 2
and 4).

-
Press button.
- Press buttons -0- and -6- to select "End Output"
function 06, and press -Q- button to confirm
input.

Pa
ge 34 of 166 Motronic Multi
port Fuel In
jection
(MFI
) and i
gnition s
ystem
11/23/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU03.24.1