1998 AUDI A8 engine

24-60
Evaluation of display group 2 Display
group: 2


Display field:
2
Possible cause
Corrective action
less than 0.50
ms
Smaller values can only occur while driving during
deceleration
more than 1.50
ms Shift into drive range (auto. transmission)
Engine is affected by additional consumers- Move shift lever to P or N
- Illuminate load (A/C, power steering,
generator)

Poor idle (does not run on all cylinders)- Check spark plugs
- Check fuel injectors Page 24
-87


Throttle valve control module -J338 faulty- Check throttle valve control module
Page 24
-99

Display field:
4
Possible cause
Corrective action
less than 1.8
g/s
Large amount of false air between intake air duct and
Mass Air Flow (MAF) sensor - Check intake air system for leaks (false
air) Page 24
-97

larger than 4.0
g/s
Shift lever in drive range (auto. transmission)
Engine affected by additional consumers- Move shift lever to P or N
- Eliminate load (A/C, power steering,
generator)
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24-63

Engine Coolant Temperature (ECT)
sensor, checking


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
Engine cold
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24-64

Checking

- Connect VAG 1551 or VAG 1552 scan tool and
press buttons -0- and -1- to insert "Engine
Electronics" address word 01 (with ignition
switched on) 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-, -0- and -1- to input display group number 1, and
press -Q- button to confirm input.
Read Measuring Value Block 1 1 2 3 4

Indicated on display (1-4 = display fields)
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24-65

- Compare display with specified value for engine
coolant temperature sensor (display field 2):

Display fields

1 2 3 4
Display group 1: Basic function, engine idle speed
Display xxxx RPM
xxx.x C
xx.x% XXXXXX
Indicates Engine
speed
(in 40 RPM
steps) Engine coolant temperature Oxygen sensor control Adjustment
conditions
Range 0-6800
RPM -46.5 to 141.0 C
-25.0 to 25.0 % ---
Specified
value 0 RPM
approx. ambient temperature
1)
Between -10.0 and 10.0%, value
must fluctuate by at least 2 % ---

--- If not as specified Page 24
-66
,
Evaluation of display group 1
--- ---
1) If indicated temperature deviates significantly from the ambient temperature, check ECT sensor wiring for resistance or
open circuits.

- Start engine and let run at idle.

Temperature value must increase evenly
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Notes:

Temperature is displayed in increments of 1.5
C.

If engine performance problems occur within
certain temperature ranges, and if the
temperature values do not increase without
interruption, the temperature signal is
intermittently interrupted and the sensor must
be replaced.
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24-66
If NOT:

- Replace Engine Coolant Temperature (ECT)
sensor -G62-.

-
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.
Evaluation of display group 1 Display group: 1


Display field: 2
Possible cause
Corrective action
approx. -46.5 C
Open circuit or short circuit in wiring to B+ - Check wiring Page 24
-66
approx. 141.0 C
Short circuit to Ground

Checking wiring

- Connect VAG 1598/22 test box to ECM harness
connector Page 01
-56
.
Pa
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24-68
If wiring is OK:

- Check ECT sensor resistance across terminal 1 (signal) and terminal 3
(ground).
- Check measured resistance value for appropriate temperature range
using graph below (N24-0157).

Range A: 0 to 50 C

Range B: 50 to 100 C

Examples:
If resistance is NOT OK:
At 30 C, ECT sensor resistance should be 1500-2000 At 80 C, ECT sensor resistance should be 275-375
- Replace Engine Coolant Temperature (ECT) sensor -G62-.
- 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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24-70

Checking

- Connect VAG 1551 or VAG 1552 scan tool and
press buttons -0- and -1- to insert "Engine
Electronics" address word 01 (with ignition
switched on) 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-, -0- and -4- to input display group number 4, and
press -Q- button to confirm input.
Read Measuring Value Block 4 1 2 3 4

Indicated on display (1-4 = display fields)
Pa
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yp
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