Problem

Windscreen heating does not work. The windscreen heating control unit recognises a short circuit. Entry e.g. under lower limit.

Technical background

The windscreen has a resistance value of under 1.9 ohm, as a result the windscreen heating control unit moves to short circuit recognition and deactivates the windscreen heating.

Production change

Modified software for the windscreen heating control unit, new minimum resistance for short circuit recognition of 1.3 ohm from chassis number 4E*6N 016 584.

Resolution

Check the resistance value of the windscreen under

address code 08 Climatronic, measured value block 46, digit 3.

If the resistance is under 1.9 ohm and the minimum value on digit 1 over 1.3 ohm, Replace the windscreen heating control unit. The new control unit must have software version SW007, check the data sticker of the control unit before the installation. 

When replacing the windscreen make sure that the new windscreen has an identification with the resistance value on the plug. It must be over 1.9 ohm.

Cars Affected: A8 2005