If you are installing a chip upgrade to your VDub you will need to know where the factory ECU is located.  

The following vehicles have the ECU located under the base of the windshield, next to the windshield wiper assembly.  A black plastic or metal cover that runs the entire length of the windshield covers the ECU.

    * Audi TT

 * VW Cabrio (MkIII chassis only)

 * VW Corrado VR6 and G60

    * VW Golf II, Jetta II

 * VW Golf III, Jetta III

 * VW Golf IV, Jetta IV

 * VW Passat (through 1997 B4 model)

The following vehicles have the ECU located in a black plastic box located in the engine compartment on the driver's side, next the firewall and brake fluid reservoir.  Five Phillips head or T30 Torx screws hold the box lid on.  Some later models may require the removal of an additional factory RF shield.

  * Audi A4 & A6

 * Audi S4

 * VW Passat (1998-up)

The following vehicle has the ECU located underneath the top panels of the dashboard.

  * VW Beetle (1998-up.)  Note: Both the center dash top and the driver's side dash top must be removed to access the ECU.

2006-up GTI 2.0T and 1.8T