Some people are having hard time with 93c86 in circuit, and even problems with it out of circuit on adapter, especially on early siemens since no diagram in xhorse vvdi prog for soldering wires to board only continental.
Usually vvdi prog failed to read all the all the 93C86 under ST and other manufacturers. Here’s the tip to do kessy modules 93C86 Touareg/A8/Porsche in circuit with vvdi-prog if failing to read all the all the 93C86 under ST and other manufacturers.
For the continental you can always solder the wires following diagram and never have problem but for Siemens there’s no diagram so have to go straight to chip.
You have to chop the 6 and 7 pins on the clip off and read as microchip 93C/LC/AA86A remember to bridge the crystal as well.
This is a Siemens VDO showing pictures of, and that the continental you would just follow diagram in vvdiprog on soldering wires straight to board to read that style.
But is always safer to remove eeprom and read the data off the board.
Credit to Mr. FaGalde.