Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Knock control stop, checking
2009 Audi A6 BaseSECTION 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
- 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.
Display on VAS5051:
- Under -1- select diagnostic function "08 - Read measured value block".
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.
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.
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 |
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| 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 |
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| One cylinder deviates significantly from the others |
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RENDER: 1.0x
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.