sensor AUDI A8 1999 D2 / 1.G AEB Engine Motronic MFI And Ignition System

24-19

- Check oxygen sensor control learning values
(display fields 1 and 2):

Display fields

1 2 3 4
Display group 32: Oxygen sensor control learning values
Display xx.x % xx.x %
Indicates Oxygen sensor control learning value at idle
(additive)
(before TWC) Oxygen sensor control learning value at partial load
(multiplicative)
(before TWC)
Range -26.0 to 26.0 % -25.0 to 25.0 %
Specified
value -8.0 to 8.0 %
(can vary slightly) -8.0 to 8.0 %
(can vary slightly)
If not as specified Page 24
-22
, Evaluation of display group 32

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. Read Measuring Value Block 33

Indicated on display (1-4 = display fields)
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24-20

- Check oxygen sensor control (display fields 1
and 2):

Display fields

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

If not as specified Page 24
-21
,
Continuation
If not as specified Page 24
-23
, Evaluation of display
group 33

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24-21

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

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

- Check Oxygen Sensor (O2S) heater Page 24
-
27
.
If the value in display field 1 remains constant:

- Check oxygen sensor voltage (display field 2).

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

- Switch ignition off.
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24-22
Evaluation of display group 32 Display group:
32


Display fields: 1
+ 2
Possible cause
Corrective action
O2S control
learning value:
-26.0 to -8.0 %
Engine oil dilution (when partial load learning value
is normal, display field 2)
- Change engine oil, or carry out extensive road
test and check again.


Fuel pressure too high- Check fuel pressure regulator Page 24
-93


Fuel injector leaking- Check fuel injectors Page 24
-87


Oxygen Sensor (O2S) heater malfunction- Check O2S heater Page 24
-27
O2S control
learning value:
8.0-26.0 %
Intake air leaks ("false air") or exhaust manifold
leaks (when partial load learning value is normal,
display field 2)
Repair Manual, 1.8 Liter 4
-Cyl. 5V Turbo
Engine Mechanical, Engine Code(s): AEB, ATW, Repair Group 26
- Check intake air system for leaks Page 24
-
97

- Check exhaust system for leaks:


Fuel pressure too low- Check fuel pressure regulator Page 24
-93


Oxygen Sensor (O2S) heater malfunction- Check O2S heater Page 24
-27
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Fuel injector does not open, or partially opens- Check fuel injectors Page 24
-87
O2S control
learning value:
constant 0.0 %
Oxygen sensor control learning not active- Check Mass Air Flow (MAF) sensor -G70-
Page 24
-57

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24-24

Checking HO2S reference voltage

- Disconnect 4-pin connector -1- (brown) for
HO2S -G39-.

If voltage is NOT OK:
If voltage is OK: - Connect multimeter US 1119 (Fluke 83 or equivalent) between harness
connector terminals 3 and 4 (to ECM), using adapter cables from VW
1594 connector test kit.
- Start engine and measure voltage.
Specified value: 0.40-0.50 volts
- Switch ignition off.
- Check HO2S wiring Page 24
-25
- Replace Heated Oxygen Sensor (HO2S) -G39-.
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24-27

Oxygen Sensor (O2S) heater (before
TWC), checking


Notes:

Harness connector for Oxygen Sensor (O2S)
heater: 4-pin, brown
Component locations Page 24
-1 .

Required special tools and test equipment

VAG 1551 or VAG 1552 Scan Tool (ST) with
VAG 1551/3 adapter cable
VAG 1598/22 test box
Multimeter US 1119 (Fluke 83 or equivalent)
VW 1594 connector test kit
Wiring diagram

Test requirements
Fuse for Oxygen Sensor (O2S) heater OK
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24-29

- Compare display and specified values (display
fields 1 and 2):

Display fields

1 2 3 4
Display group 41: Oxygen Sensor (O2S) heating
Display
xx.x
Htg.bC.ON/Htg.bC.OFF
xx.x
Htg.aC.ON/Htg.aC.OFF
Indicates Resistance of oxygen
sensor heater
(before TWC) O2S heater on
or
O2S heater off
(before TWC) Resistance of oxygen
sensor heater
(after TWC) O2S heater on
or
O2S heater off
(after TWC)
Range
0.0-65.0
--- --- ---
Specified
value 4.9-19.9
Htg.bC.ON --- ---

If not as specified Page 24
-30
, Continuation
--- ---
If displayed values are OK (as specified):

-
Press button to advance program
sequence.
-
Press buttons -0- and -6- to select "End Output"
function 06, and press -Q- button to confirm
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24-30

Continuation

- Disconnect 4-pin connector -1- (brown) for
Heated Oxygen Sensor (HO2S) -G39-.

If resistance is NOT OK: - Connect multimeter US 1119 (Fluke 83 or equivalent) between HO2S
connector terminals 1 and 2, using VW 1594 connector test kit.
- Measure resistance.

Specified value: 0.0-19.9 - Replace Heated Oxygen Sensor (HO2S) -G39-.
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24-35

Oxygen Sensor (O2S) behind Three Way
Catalytic Converter (TWC) and oxygen
sensor control, checking


Notes:

Harness connector for Oxygen Sensor (O2S)
behind Three Way Catalytic Converter (TWC):
4-pin, black
Component locations Page 24
-1

Required special tools and test equipment

VAG 1551 or VAG 1552 Scan Tool (ST) with
VAG 1551/3 adapter cable
VAG 1598/22 test box
Multimeter US 1119 (Fluke 83 or equivalent)
VW 1594 connector test kit
Wiring diagram

Test requirements

Pa
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(MFI
) and i
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11/19/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU02.24.1