Common Diagnostic Procedures
Updated 14 February 2022

These pages detail some common vehicle-specific procedures that can be performed with VCDS. These are not a substitute for the correct Factory Repair Manual for your vehicle. Ross-Tech is not responsible for any damage or problems that may result from following these instructions. They are to be used at your own risk. We will be adding more pages periodically and welcome any comments or suggestions to

Ross-Tech Wiki

This is an encyclopedia of information such as common Fault Codes and Diagnostic Procedures. (Beta - This site is continually having content added and will eventually be the primary resource for information on usage of VCDS)
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Application Charts showing Which Interface works with each vehicle
(Which controllers are in my car and where do I find the diagnostic port?)

2005.5+ VW MkV Jetta/Rabbit/GTI (Wiki)
1998-2004 VW MkIV Golf/Jetta/New Beetle
1998-2004 VW Passat B5
2004+ VWTouareg
2008+ Audi A5/S5 (8T/B8)
2008+ Audi A4/S4/RS4 (8K/B8)
2002+ Audi A4/S4/RS4 (B6/B7)
1995-2001 Audi A4/ 2000-2003 Audi S4 (B5/8D)

Immobilizer Information for VW/Audi/Seat/Skoda
(information about how Immobilizer works and what procedures are available to deal with it in the Ross-Tech Wiki)

Important Note: Unless you ALREADY have the SKC information for your vehicle and components then you will NOT be able to do any of the Immobilizer functions.

Click this link for more information.

Non-Immo Instrument Cluster swapping

Common procedures

Some useful off-site links
Some excellent Excel spreadsheets that use data from VCDS (thanks to
Right-click, save-as

Air/Fuel calculation spreadsheet - This generates an A/F graph from injector pulse widths, airflow, etc.

Block 120 spreadsheet - This generates a Horsepower and Torque graph using the calculated torque values output by Bosch ME7 ECU's.

Block 115 spreadsheet - This generates a boost graph using the MAP sensor readings for drive-by-wire 1.8T and 2.7T engines.

Stoney's Audi A6 FAQ
All sorts of AudiWorld threads about diagnostics.

Paul Waterloo's AudiPages Audi A8 Transmission Coding Page
Transmission recoding for sportier performance.

The "Butt Dyno" Spreadsheet
How to calculate wheel horsepower and torque from acceleration and deceleration data.

Shiftpoints Analysis Spreadsheet
How to determine shiftpoints for optimal acceleration.
A great thread on using VAG-COM to permanently alter Audi Allroad suspension height. This is also known as the 402 Mod.

Automobile Museums Map
A map of automotive related museums in the United States

Good sources to learn more about what you can do with your car:
Ross-Tech Sponsored Forums:

Ross-Tech Forum (This is the official forum for VCDS Support)

AudiWorld VCDS VW/Audi Computer Diagnostics Forum

VWVortex VCDS Diagnostics Forum

Audi race car
Ross-Tech customer Dave Coughlin's S4,
ready to run in the 2002 One-Lap

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Ross-Tech is not affiliated with the Volkswagen Group in any way.