2000 AUDI A4 display

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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24-23
Evaluation of display group 33 Display group:
33


Display field: 2
Possible cause
Corrective action
approx. 0.435
V
Open circuit in wiring between HO2S connector terminal 4 and
ECM - Check reference voltage Page
24
-24
.
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 Page 24
-
25
.
approx. 0.000
V
Short circuit to Ground between HO2S connector terminal 4
and ECM
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24-28

Checking

- Connect VAG 1551 or VAG 1552 scan tool and
press buttons -0- and -1- to insert "Engine
Electronics" address word 01 (with engine
running at idle) Page 01
-7 .
Rapid data transfer
HELP
Select function XX

Indicated on display
- Press buttons -0- and -8- to select "Read Measuring Value Block"
function 08, and press -Q- button to confirm input.
Read Measurin
g Value Block
HELP
Input displa
y group number XXX

Indicated on display
- Press buttons -0-, -4- and -1- to input display group number 41, and
press -Q- button to confirm input.
Read Measuring Value Block 41 1 2 3 4

Indicated on display (1-4 = display fields)
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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
Pa
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24-31
If resistance is OK:

- Switch multimeter to 20 VDC measuring
range.

If display = Htg.bC.ON:
If display switches between "Htg.bC.ON" and "Htg.bC.OFF:" - Connect multimeter between harness connector terminals 1 and 2 (to
ECM), using VW 1594 connector test kit.
- Measure voltage supply and check display in display group 41, display
field 2.
Specified value: 11.0-14.5 volts Specified value: 0.0-12.0 volts (oscillating)
Pa
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24-33
If there is voltage:

If display = Htg.bC.ON:
If display switches between "Htg.bC.ON" and "Htg.bC.OFF:" - Connect multimeter between harness connector terminal 2 (to ECM)
and Battery Positive Voltage (B+), using VW 1594 connector test kit.
- Measure voltage supply and check display in display group 41, display
field 2.
Specified value: 11.0-14.5 volts Specified value: 0.0-12.0 volts (oscillating)
- Switch ignition off.
Pa
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