Checking knock sensor and knock control: VW (ABA)

Special tools, testers and auxiliary items

Fault reader V.A.G 1551 or vehicle system tester V.A.G 1552 with cable V.A.G 1551/3
Test box V.A.G 1598/18
Hand multimeter V.A.G 1526 or multimeter V.A.G 1715
Adapter set V.A.G 1594
Current flow diagram

Test sequence

Connect fault reader V.A.G 1551 (V.A.G 1552) and select engine electronics control unit with the "Address word" 01. When doing this the engine must be running at idling speed.
(Connecting fault reader and selecting engine electronics control unit => Page
01-6
.)

Rapid data transfer
HELP
Select function XX
Indicated on display:

Press keys 0 and 8 for the function "Read measured value block" and confirm entry with Q key.

Read measured value block
HELP
Input display group number XXX
Indicated on display:

Press keys 0, 4 and 5 for "Display group number 45" and confirm entry with Q key.

Read measured value block 45
⇒
1
2
3
4
Indicated on display:
(1...4 = Display zones)

Note:

The check must be carried out during a test drive as the knock control is only active with an engine load exceeding 3 ms.

Carry out a test drive and observe the knock control specifications on display (2nd person necessary).

Display zones
1 · 2 · 3 · 4
Display group 45: Knock control
Display · xx.xx °CS · xx.xx °CS · xx.xx °CS · xx.xx °CS
Indicated · Ignition angle correction Cylinder 1 · Ignition angle correction Cylinder 2 · Ignition angle correction Cylinder 3 · Ignition angle correction Cylinder 4
Working range · 0.0...15.0 °CS · 0.0...15.0 °CS · 0.0...15.0 °CS · 0.0...15.0 °CS
Specification · 0.0...12.0 °CS · 0.0...12.0 °CS · 0.0...12.0 °CS · 0.0...12.0 °CS
If specification is not attained =>Page , evaluating display group 45 28-25

Read-out the readiness code=> Page
01-34
.
Press ⇒key.
Press keys 0 and 6 for the "End data transfer" function and confirm input with the Q key.

Evaluating display group 45

Display group: 45 / Display zone: 1...4 · / Possible fault cause · / Fault elimination
All cylinders more than 12 °CS · Knock sensor defective · - Continued => Page 28-26
Connector corroded
Knock sensor not correctly tightened · - Loosen knock sensor and tighten to 20 Nm
Ancillary components on engine loose · - Secure ancillary components
Poor fuel quality · - Change type of fuel
One cylinder deviates greatly from the others · Connector corroded · - Continued => Page 28-26
Engine damage · - Check compression pressure / => Repair group 13
Ancillary components on engine loose · - Secure ancillary components

Continuation

Separate brown 3 pin connector -2- to knock sensor 1 (G61) -1-.
Connect multimeter using aux. cables from V.A.G 1594 to measure resistance and measure resistance between contacts 1+2, 1+3 and 2+3 on connector to knock sensor.
Specification ∞ω

If the specification is attained:

Connect test box V.A.G 1598/18 to control unit wiring loom -arrow-.

Check wiring between test box and 3 pin connector for open circuit according to current flow diagram.
Contact 1+socket 34
Contact 2+socket 33
Contact 3+socket 56
Wire resistance: Max. 1.5 ω
Additionally check wires for short to one another.
Contact 3+socket 34
Contact 3+socket 33
Contact 2+socket 34
Specification: ∞ω

If no wiring fault is detected:

Loosen knock sensor and tighten again to 20 Nm.

If the fault is still present (fault again in fault memory):

Replace knock sensor (G61) =>Page
28-3
, item
10
.
Read-out the readiness code=> Page
01-34
.