1999 AUDI A4 sensor

28-29

Coolant temperature sensor with oval
connector:

All:
Scale A shows resistance values for temperature range 0 - 50 C and
scale B the values for temperature range 50 - 100 C. - Connect multi-meter (resistance measurement) between terminals 3
and 4 of sensor.

Examples:
If value does not match the specification:
30 C corresponds to a resistance from 1500...2000 80 C corresponds to a resistance from 275...375
- Replace coolant temperature sensor.
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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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28-34

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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28-40
Evaluation display groups 20/21/22/23/24, - Ignition timing angle retard Indicated on display
Malfunction cause
Corrective action
All cylinders greater
than 12 KW
Knock sensor faulty- Check knock sensor Page 28
-41
.


Corroded connection

Knock sensor incorrect
tightening torque - Loosen and tighten knock sensor with 20 Nm (15 ft lb)

Components on engine
loose - Tighten components

Low fuel grade- Change fuel grade
One cylinder deviates
clearly from others Corroded connection- Check knock sensor Page 28
-41
.


Engine damage
Repair Manual, 2.7 Liter V6 5V BiTurbo Engine Mechanical, Engine
Code(s): APB, Repair Group 15, Cylinder head removing, check compression pressure
- Check compression pressure:


Components on engine
loose - Tighten components
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28-41

Knock Sensor (KS) 1 -G61 and Knock
Sensor (KS) 2 -G66, checking


Notes:

It is not possible to carry out an electrical test of
the knock sensors themselves.
To ensure that the knock sensors function
properly it is important to keep exactly to the
specified tightening torque of 20 Nm (15 ft lb)
Use only gold-plated terminals when repairing
the terminals in the plug connectors for the
knock sensors.
Check for corrosion in connection between
knock sensor and wiring harness.

Checking knock sensors

Note: - Disconnect harness connector for relevant knock sensor in engine
compartment.
Component location overview Page 24
-5 .
In order to reach the connector for the knock sensor for cylinder bank
2, first remove the bolts securing the coolant reservoir and move the
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28-42


If there is a connection between the terminals.
Notes:
If there is no short circuit
Checking wiring between knock sensors and engine control module - Check for short circuits between all three terminals in knock sensor
connector (terminals 1 + 2, 1 + 3 and 2 + 3).
Specified value: There must be no contact between the wires (infinite
). - Replace knock sensor.
In order to reach the knock sensors, first remove the air duct Page 24
-43
.
Use special tool 3247 to remove the knock sensors.
- Check wiring for knock sensors.

- Connect VAG1598/31 test box to wiring harness for engine control
module. Do not connect to the engine control module itself Page 24
-
20
.
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28-43


- Check wiring connection from relevant sensor connector to...

- ....Engine Control Module (ECM) for open circuit and/or short to B+ or
Ground (GND).
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28-44

Knock Sensor (KS) 1 -G61 (Bank 1)
3-pin connector on
wiring harness, socket
VAG1598/31 test
box, socket
1 (Ground (GND)) 99
2 (signal) 106
3 (shielded) 108
Knock sensor (KS) 2 -G66 (Bank 2)
3-pin connector on
wiring harness, socket
VAG1598/31 test
box, socket
1 (Ground (GND)) 99
2 (signal) 107
3 (shielded) 108

Resistance in wiring: max. 1.5 ohm

- Repair any open/short circuit as necessary.
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