sensor AUDI A6 1999 C5 / 2.G ATQ Engine Ignition System Checking User Guide

28-26

Coolant temperature sensor with square
connector:

Coolant temperature sensor with oval connector: - Connect multimeter between terminal 1 and 3 of connector for
resistance measurement.

- Connect multimeter between terminal 3 and 4 of connector for
resistance measurement.
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28-27

All models
Range A shows the resistance values for the
temperature range from 0-50 C, and range B
shows the values for the temperature range from
50-100 C.

Read-out examples:
If specified value is not obtained:
If specified value is obtained:
30 C corresponds to a resistance of 1500 to 2000 80 C corresponds to a resistance of 275 to 375
- Replace coolant temperature sensor.
- Connect VAG1598/31 test box at wiring harness to ECM, do not
connect ECM Page 24
-17
.
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28-28

Coolant temperature sensor with square
connector:

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

- Check the following wire connections for open circuit and short circuit
to Ground (GND) and B+: Harness connector
Terminal
VAG1598/31 test box
Socket
3 108
4 (signal) 93
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28-33

Knock recognition control stop,
checking

The following tests must be performed when a
DTC is stored that relates to "knock recognition
control limit reached".

Possible cause
Corrective action
DTC for all cylinders
Poor fuel quality- Change fuel quality
(see operating instructions)
or
DTC for all cylinders in one
row Knock sensor tightened to incorrect
torque - Loosen knock sensors and tighten to 20
Nm
Knock sensor faulty- Check knock sensors Page 28
-41

Corrosion at harness connector
Engine accessories loose- Secure engine accessories
DTC for one Cylinder Engine damage- Check compression pressure
Engine accessories loose- Secure engine accessories

- Also check ignition angle retardation of the
individual cylinders Page 28
-34
.
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28-35


Display fields

1 2 3 4
Display group 020: Ignition -knock control in driving operation
Display
xx.x KW
xx.x KW
xx.x KW
xx.x KW
Indicated
Ignition angle
retardation cylinder 1
via knock control
Knock sensor control Ignition angle
retardation cylinder 2
via knock control
Knock sensor control Ignition angle
retardation cylinder 3
via knock control
Knock sensor control Ignition angle
retardation cylinder 4
via knock control
Knock sensor control
Specified
value 0 to 12 KW
0 to 12 KW
0 to 12 KW
0 to 12 KW
Notes Evaluation Page 28
-40

Note:
The number values indicated in display fields 1 to 4 represent actual ignition angle retardation via knock control of the
individual cylinders. Ignition angle retardation occurs in KW (crankshaft degrees) toward retardation.
- Press -C- button.Read Measuring Value Block
Q
Input display group number XXX

When indicated on display:
- Press buttons -0-, -2- and -1- to select "display group number 021" and press -
Q- button to confirm input.
Read Measuring Value Block 21
1
2
3
4

When indicated on display:
- Check indication in display field 1 and 2.
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28-36


Display fields

1 2 3 4
Display group 021: Ignition -knock control in driving operation
Display
xx.x KW
xx.x KW


Indicated
Ignition angle retardation cylinder 5 via
knock control
Knock sensor control Ignition angle retardation cylinder 6 via
knock control
Knock sensor control

Specified
value 0 to 12 KW
0 to 12 KW


Notes Evaluation Page 28
-40



Note:
The number values indicated in display fields 1 and 2 represent actual ignition angle retardation via knock control of the
individual cylinders. Ignition angle retardation occurs in KW (crankshaft degrees) toward retardation.
- Press -C- button.Read Measurin
g Value Block
Q
Input displa
y group number XXX

When indicated on display:
- Press buttons -0-, -2- and -2- to select "display group number 022" and press -Q-
button to confirm input.
Read Measuring Value Block 22
1
2
3
4

When indicated on display:
- Check indications in display field 3 and 4.
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28-37


Display fields

1 2 3 4
Display group 022: Ignition -knock control in driving operation
Display xxxx/min xxx.x %
xx.x KW
xx.x KW
Indicated Engine speed
(RPM) Engine
load Ignition angle retardation cylinder 1
via knock control
Knock sensor control Ignition angle retardation cylinder 2
via knock control
Knock sensor control
Specified
value xxxx/min 12 to 100
% 0 to 12 KW
0 to 12 KW
Notes Evaluation Page 28
-40

Note:
The number values indicated in display fields 3 and 4 represent actual ignition angle retardation via knock control of cylinders
1 and 2. Ignition angle retardation occurs in KW (crankshaft degrees) toward retardation.
- Press -C- button.Read Measurin
g Value Block
Q
Input displa
y group number XXX

When indicated on display:
- Press buttons -0-, -2- and -3- to select "display group number 023" and press -Q-
button to confirm input.
Read Measuring Value Block 23
1
2
3
4

When indicated on display:
- Check indications in display field 3 and 4.
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28-38


Display fields

1 2 3 4
Display group 023: Ignition -knock control in driving operation
Display xxxx/min xxx.x %
xx.x KW
xx.x KW
Indicated Engine speed
(RPM) Engine
load Ignition angle retardation cylinder 3
via knock control
Knock sensor control Ignition angle retardation cylinder 4
via knock control
Knock sensor control
Specified
value xxxx/min 12 to 100
% 0 to 12 KW
0 to 12 KW
Notes Evaluation Page 28
-40

Note:
The number values indicated in display fields 3 and 4 represent actual ignition angle retardation via knock control of cylinders
3 and 4. Ignition angle retardation occurs in KW (crankshaft degrees) toward retardation.
- Press -C- button.Read Measurin
g Value Block
Q
Input displa
y group number XXX

When indicated on display:
- Press buttons -0-, -2- and -4- to select "display group number 024" and press -Q-
button to confirm input.
Read Measuring Value Block 24
1
2
3
4

When indicated on display:
- Check indications in display field 3 and 4.
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28-39


Display fields

1 2 3 4
Display group 024: Ignition -knock control in driving operation
Display xxxx/min xxx.x %
xx.x KW
xx.x KW
Indicated Engine speed
(RPM) Engine
load Ignition angle retardation cylinder 5
via knock control
Knock sensor control Ignition angle retardation cylinder 6
via knock control
Knock sensor control
Specified
value xxxx/min 12 to 100
% 0 to 12 KW
0 to 12 KW
Notes Evaluation Page 28
-40

Note:
The number values indicated in display fields 3 and 4 represent actual ignition angle retardation via knock control of cylinders
5 and 6. Ignition angle retardation occurs in KW (crankshaft degrees) toward retardation.
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28-40
Evaluation display groups 020/021/022/023/024 - ignition angle retardation
Indicated on display
Possible cause
Corrective action
All cylinders more than 12 KW
Knock sensor faulty- Check knock sensor Page 28
-41

Harness connector corroded
Knock sensor incorrect
tightening torque - Loosen knock sensors and tighten to 20
Nm
Engine accessories loose- Secure engine accessories
Poor fuel quality- Change fuel quality
(see operating instructions)
One cylinder deviates significantly from
the others Harness connector corroded- Check knock sensor Page 28
-41

Engine damage
Repair Manual, Engine Mechanical,
Repair Group 15 - Check compression pressure:

Engine accessories loose- Secure engine accessories
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