1997 AUDI A4 check engine

28-25

Engine Coolant Temperature (ECT)
sensor -G62, checking


Note:
Component location of coolant temperature
sensor Page 24
-5 .

Test conditions

Engine cold

- Connect vehicle diagnostic, testing and
information system VAS 5051 or VAG1551 scan
tool to vehicle and select engine electronics
control module by entering address word "01"
Page 01
-9 .

When doing this the engine must be at idle.
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28-27


Display fields

1 2 3 4
Display Group 004: Coolant temperature with engine idle
Display xxxx RPM xx.xxx V
xxx.x C
xxx.x C
Indicates Engine speed RPM Battery voltage
Coolant temperature Intake air temperature
Specified value XXXX RPM 12.000...14.500 V
Temperature must increase evenly Ambient temperature
until 120 C
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28-30
If the value does match the specification:

- Connect test box VAG1598/31 to wiring harness
for engine control module. Do not connect to the
engine control module itself. Page 24
-20
.

Coolant temperature sensor with square
connector:

Coolant temperature sensor with oval connector: - Check following wiring connections for open circuits and short circuits
to B+ or Ground (GND) Harness connector
Terminal
VAG1598/31 test box
Socket
1 (Signal) 93
3 108

- Check following wiring connections for open circuits and short circuits
to B+ or Ground (GND) Harness connector
Terminal
VAG1598/31 test box
Socket
3 108
4 (Signal) 93
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28-31

All:

- Check wiring for short circuit to each other.

- If necessary eliminate open circuit or short
circuit.
If no malfunction is identified in the wiring:

- Replace Engine Control Module (ECM) Page
24
-24
.
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28-32

Control module voltage supply,
checking


Test requirements:

Fuse for Engine Control Module (ECM) OK

Electrical Wiring Diagrams, Troubleshooting &
Component Locations

Battery voltage at least 11 V
Generator OK

- Connect test box VAG1598/31 to wiring harness
for engine control module. Do not connect to the
engine control module itself. Page 24
-20
.

- Switch ignition on.

Note:

The B+ voltage supply for the engine control
module comes via terminal 3 (terminal 15) and
terminal 62 (terminal 30).

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The Ground (GND) connection for the engine
control module is via terminals 1 and 2.
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28-34

Knock sensor control limit, checking

If the malfunction message "Knock control
regulation reached" is recorded in the DTC
memory the following tests must be carried out.
See also measuring value blocks 20, 21, 22, 23
and 24 Page 28
-35


Possible cause of malfunction
Corrective action
Malfunction
message relating to all cylinders
Poor fuel quality- Change to higher quality fuel (see Owner's
Manual)
or
malfunction
message relating to all cylinders in
one bank Incorrect tightening torque on
knock sensor - Loosen knock sensor, then tighten to 20
Nm (15 ft lb)
Knock sensor faulty- Check knock sensor Page 28
-41
.

Corrosion on connector
Loose components on engine- Secure loose components
Malfunction
message relating to one cylinder Mechanical engine damage- Check compression pressure
Loose components on engine- Secure loose components
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28-37

Display Group 22 -Ignition- Knock control

Driving mode
Read measuring value block
22
Indicated on display

xx.x RPM x.x %
xx.x KW
xx.x KW



1 2
3 4
Display fields
Specified value
Evaluation


Ignition timing retard via knock control:
cylinder 2 0...12 KW
(crankshaft
angle)
Page 28
-40




Ignition timing retard via knock control:
cylinder 1
0...12 KW
(crankshaft
angle)
Page 28
-40



Engine load 15 - 175 %

Engine speed RPM
750 - 6800 RPM

Note:
The displayed digit values in display fields 3 and 4 reflects the actual "ignition timing retard" via knock control from cylinders 1
and 2. The ignition timing retard occurs via KW (crankshaft angle).
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