AUDI A6 1998 C5 / 2.G AHA Engine Multiport Fuel Injection And Ignition System Owner's Guide

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.
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Read Measuring Value Block 33 1 2 3 4

Indicated on display (1-4 = display fields)
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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
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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.

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- Switch ignition off.
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24-27
Evaluation of display group 32 Display group:
32


Display fields:
1-4
Possible malfunction cause
Corrective action
O2S control
learning value:
-25.0 to -10.0
%
Engine oil dilution (when part load learning value is
normal display fields 2 and 4)
- Change engine oil, or carry out extensive
road test and check again


Fuel pressure too high- Check fuel pressure regulator page 24
-
111



Fuel injector leaking- Check fuel injectors page 24
-102


Oxygen Sensor (O2S) heater malfunction- Check O2S heater page 24
-34
O2S control
learning value:
10.0 to 25.0 %
Intake air leaks ("false air") or exhaust manifold leaks
(when partial load learning value is normal display
fields 2 and 4)
- Check intake air system for leaks page 24
-126

- Check exhaust system for leaks Repair
Manual, 2.8 Liter V6 5V General, Engine,
Repair Group 26


Fuel pressure too low- Check fuel pressure regulator page 24
-
111



Oxygen Sensor (O2S) heater malfunction- Check O2S heater page 24
-34
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Fuel injector does not open, or partially opens- Check fuel injectors page 24
-102
O2S control
learning value:
constant 0.0 %
Oxygen sensor control learning not active- Check Mass Air Flow (MAF) sensor -G70-
page 24
-68

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24-28
Evaluation of display group 33 Display group:
33


Display fields:
2, 4
Possible malfunction cause
Corrective action
approx. 0.435 V

Open circuit in wiring between HO2S connector terminal
4 and ECM - Check reference voltage page 24
-29
approx. 0.435 V

Open circuit in wiring between HO2S connector terminal
3 and ECM
approx. 1.085 V
Short circuit to positive (B+) between HO2S connector
terminal 4 and ECM - Check HO2S wiring, bank 1, sensor 1
page 24
-30

- Check HO2S wiring, bank 2, sensor 1
page 24
-32

approx. 0.000 V

Short circuit to Ground between HO2S connector
terminal 4 and ECM
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24-29

Checking HO2S reference voltage (Banks 1,
2)

- Disconnect 4-pin connector for respective
HO2S.

If voltage is NOT OK:
If voltage is OK: - Connect multimeter US1119 (Fluke 83 or equivalent) between harness
connector terminals 3 and 4 (to ECM), using adapter cables from
VW1594 connector test kit.
- Start engine and measure voltage.
Specified value: 0.40-0.50 volts
- Switch ignition off.
- Check HO2S wiring.

Bank 1, sensor 1 page 24
-30
.

Bank 2, sensor 1 page 24
-32
.
- Replace respective Heated Oxygen Sensor (HO2S).
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24-30

Checking HO2S wiring, bank 1, sensor 1

- Disconnect 4-pin connector (black) for HO2S -
G39-.

- Connect VAG1598/22 test box to ECM harness
connector page 01
-67
.

- Check wiring for open circuit between ECM/test box and 4-pin HO2S
harness connector (to ECM).

Connector terminal 3 to ECM/test box socket 25
Connector terminal 4 to ECM/test box socket 26
Specified value: max. 1.5
- Check wiring for short circuits between terminals of 4-pin connector,
and between connector and ECM/test box.

Connector terminal 4 to ECM/test box socket 25
Specified value:
- Check wiring for short circuits to wiring harness shielding.

Connector terminal 4 to ECM/test box socket 14
Connector terminal 3 to ECM/test box socket 14
Specified value:
Pa
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) and i
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