1999 AUDI A8 check engine

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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24-38

Continuation
If displayed values are NOT OK (not as
specified):

- Road test to condition oxygen sensor (eliminate
possible contamination) and repeat test.
If the values in display fields 1 and 2 are still
NOT OK:

- Check Oxygen Sensor (O2S) heater Page 24
-
43
.

- Briefly accelerate engine over 3000 RPM.
If the value in display field 1 remains constant:
page Page 24
-39
, Evaluation of display group
36.
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24-40

Checking HO2S reference voltage

- Disconnect 4-pin connector (black) for Oxygen
Sensor (O2S) behind Three Way Catalytic
Converter (TWC) -G108-.

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 to 0.50 volts
- Switch ignition off.
- Check HO2S wiring Page 24
-41
- Replace HO2S behind TWC -G108-.
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24-44

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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24-51

Oxygen Sensor (O2S) aging, checking


Required special tools and test equipment

VAG 1551 or VAG 1552 Scan Tool (ST) with
VAG 1551/3 adapter cable

Test requirements
Engine Coolant Temperature (ECT) at least
85 C (185 F)
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24-53


Display fields

1 2 3 4
Display group 34: Oxygen sensor aging (time period check of oxygen sensor)
Display xxxx RPM xx.xx ms xx.xx s Test OFF/Test ON
B1-S1 OK/B1-S1 n.OK
Indicates Engine speed
(in 40 RPM steps) Engine load Time period oxygen sensor Diagnostic status
Diagnostic result
Range 0-6800 RPM 0.00-8.50 ms 0.00-5.00 s ---
Specified value 1800-2200 RPM 0.8-2.0 ms 0.00-3.30 s B1-S1 OK

--- --- If not as specified Page 24
-54
, Continuation
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24-55

Engine operating conditions (engine
electronics), checking


Note:
This test checks whether the Motronic Engine
Control Module (ECM) -J220- recognizes the
engine operating conditions.

Required special tools and test equipment

VAG 1551 or VAG 1552 scan tool with VAG
1551/3 adapter

Test requirements
Engine oil temperature at least 80 C (176
F)

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.
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24-56

- Check engine operating conditions (display field
4):

Display fields

1 2 3 4
Display group 5: Engine electronics-operating conditions
Display xxx RPM xx.xx ms xxx km/h Idle
Part throt
Full throt
1)

Decel
Enrich
Indicates Engine speed
(in 40 RPM steps) Engine load Vehicle speed Operational condition
Range 0-6800 RPM 0.00-8.50 ms --- ---
Specified value 760-960 RPM 0.50-1.50 ms 0 km/h Idle: "Idle"
Throttle slightly open: "Part throt"
Throttle quickly closed: "Decel"
Quick acceleration over 3000 RPM: "Enrich"
1) Possible only while driving
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11/19/2002 htt
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yp
e=re
pair&id=AUDI.B5.FU02.24.1