2000 AUDI A8 sensor

24-41

Checking HO2S wiring

- Connect VAG 1598/22 test box to ECM harness
connector Page 01
-56
.

- Disconnect 4-pin connector (black) for Heated
Oxygen Sensor (HO2S) behind Three Way
Catalytic Converter (TWC) -G108-.

- 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 51
Connector terminal 4 to ECM/test box socket 52
Specified value: max. 1.5
- Check wiring for short circuits between terminals of 4-pin connector,
between connector, ECM/test box, and shielding for wiring harness.

Connector terminal 4 to ECM/test box socket 51
Connector terminal 3 to ECM/test box socket 2
Connector terminal 4 to ECM/test box socket 2
Specified value:
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24-43

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


Notes:

Harness connector for Oxygen Sensor (O2S)
heater: 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
Fuse for Oxygen Sensor (O2S) heater OK
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24-45

- Compare display and specified values (display
fields 3 and 4):

Display fields

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

--- --- If not as specified Page
24
-46
, Continuation
---
If displayed values are OK (as specified):

-
Press button to advance program
sequence.
-
Press buttons -0- and -6- to select "End Output"
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24-46

Continuation

- Disconnect 4-pin connector (black) for Oxygen
Sensor (O2S) 2 -G108- behind Three Way
Catalytic Converter (TWC).

If resistance is NOT OK:
If resistance is 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: 0.00-19.9 - Replace Heated Oxygen Sensor (HO2S) behind TWC -G108-.
- Switch multimeter to 20 VDC measuring range.
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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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24-52

Function test

- 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 -4- to select "Basic Setting" function 04, and
press -Q- button to confirm input.
System in Basic Settin
g
HELP
Input displa
y group number XXX

Indicated on display
- Press buttons -0-, -3- and -4- to input display group number 34, and
press -Q- button to confirm input.
System in Basic Setting 34 1 2 3 4

Indicated on display (1-4 = display fields)
Note:
To be sure that the temperature is within the specified range, the specified
RPM has to be maintained for at least 1 minute. Observe status of oxygen
sensor control in display field 4. - Increase engine speed to 1800-2200 RPM and compare display with
specified values for oxygen sensor aging (display fields 1-4).
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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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24-54

Continuation
If displayed value is NOT OK (not as specified):

- Road test to condition oxygen sensor (eliminate
possible contamination) and repeat test.
If displayed value is still NOT OK:

- Replace HO2S -G39-.

- Check readiness code Page 01
-59
. If
Diagnostic Trouble Code (DTC) memory has
been erased, or ECM was disconnected,
generate new readiness code Page 01
-62
.
Pa
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) and i
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11/19/2002 htt
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yp
e=re
pair&id=AUDI.B5.FU02.24.1