Knock control stop, checking

WARNING: This page is about a different car, the 2006 Audi A4, 2005 Audi A4, 2004 Audi A4, 2003 Audi A4, and 2002 Audi A4. However, it is still accessible from the selected car via links, so may be relevant.

If a malfunction entry relating to "knock control stop reached" is made, perform the following checks:

Special tools and equipment

Fig 1: Identifying Vehicle Diagnosis, Testing And Information System VAS 5051

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VAS5051 with VAS5051/1

Test sequence

Connect testing and information system VAS5051. Refer to Vehicle diagnostic, testing and information system VAS5051, connecting and select functions and select vehicle system "01 - Engine electronics" in selection. Engine must be running at idling speed.

Fig 2: Diagnostic System VAS 5051: Display

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Display on VAS5051:

Under -1- select diagnostic function "08 - Read measured value block".

Fig 3: Diagnostic System VAS 5051: Display

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Display on VAS5051:

1 - Enter display group max. input value = 255

Enter "020" for "display group number 020" in zone -2- and confirm entry by pressing -Q- button.

Fig 4: Diagnostic System VAS 5051: Display

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Display on VAS5051:

Check indication in display fields -1- to -4-.

	Display zones
	1	2	3	4
Display group 020: Ignition knock control during driving
Display	xx.x°CA	xx.x°CA	xx.x°CA	xx.x°CA
Display	Ignition angle retardation cylinder 1 through Knock control	Ignition angle retardation cylinder 2 through Knock control	Ignition angle retardation cylinder 3 through Knock control	Ignition angle retardation cylinder 4 through Knock control
Specif. value	0 to 12°CA	0 to 12°CA	0 to 12°CA	0 to 12°CA
Note:	Evaluation. Refer to Evaluation of ignition angle retardation

NOTE: The numbers displayed in display zones 1 to 4 represent the actual ignition timing retardation due to the knock control of the individual cylinders. The ignition angle retardation is carried out late in °CA (crankshaft degrees).

To change to display group 021, press s button.

Fig 5: Diagnostic System VAS 5051: Display

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Display on VAS5051:

Check indication in display fields -1- and -2-.

	Display zones
	1	2	3	4
Display Group 021: Ignition knock control during driving
Display	xx.x°CA	xx.x°CA
Display	Ignition angle retardation cylinder 5 through Knock control	Ignition angle retardation cylinder 6 through Knock control
Specif. value	0...12°CA	0...12°CA
Note:	Evaluation. Refer to Evaluation of ignition angle retardation

NOTE: The numbers displayed in display zones 1 and 2 represent the actual ignition timing retardation due to the knock control of the individual cylinders. The ignition angle retardation is carried out late in °CA (crankshaft degrees).

Exit function "08 - Read measured value block" by pressing ← button.

Evaluation of ignition angle retardation

Indicated on display	Possible causes of malfunction	Corrective action
All cylinders greater than 12°CA	Knock sensor faulty	Check knock sensor. Refer to Knock sensors, checking
	Connector corroded
	Knock sensor incorrectly tightened	Loosen knock sensor and tighten to 20 Nm.
	Loose components on engine	Secure components
	Poor fuel quality	Change fuel quality (see operating instructions)
One cylinder deviates significantly from the others	Connector corroded	Check knock sensor. Refer to Knock sensors, checking
	Engine malfunction	Check compression: Refer to 15 ENGINE - CYLINDER HEAD, VALVETRAIN
	Loose components on engine	Secure components