audi Workshop Repair Guides

Audi Workshop Service and Repair Manuals

Testing knock sensors > < Testing voltage supply for control unit
Motronic injection and ignition system (4-cyl. turbo)
Testing ignition system
Testing knock sensor control limit

If the fault message "Knock sensor - control limit reached" is recorded in the fault memory the following tests must be carried out:

Possible cause of fault

Fault remedy

Fault message relating to all cylinders

- Poor fuel quality

- Change to higher quality fuel
=> Owner's Manual

or
cylinders 1/2 or 3/4

- Wrong tightening torque on knock sensor

- Loosen knock sensor, then tighten to 20 Nm

- Knock sensor defective

- Test knock sensor

- Corrosion on connector

- Check connectors

- Loose components on engine

- Secure loose components

Fault message relating to one cylinder

- Mechanical engine fault

- Test compression pressure

- Loose components on engine

- Secure loose components

Testing knock sensors > < Testing voltage supply for control unit