VCDS (VAG-COM Diagnostic System) is an On Board Diagnostic (OBD) tool that can read a lot of modules in the ECU of your VAG car. Most of the models of Audi, Volkswagen, Seat and Skoda from roughly 1990 until present, petrol and diesel engined cars. Some other car manufacturers have used VAG engines and on these cars VCDS could also work. Not always though!
VCDS is the cheaper alternative for the VAG dealer tools like VAG-1551 and VAG-1552.
VCDS, an acronym for “VAG-COM Diagnostic System”, is a third party Microsoft Windows-based software package, developed and produced by Ross-Tech, LLC since May 2000.
It is also known as VAG-COM It is primarily used for diagnostics and adjustments of Volkswagen Group motor vehicles, including Volkswagen Passenger Cars, Audi, SEAT, and Škoda automobiles, along with Volkswagen Commercial Vehicles. The name “VAG-COM” derives from the acronym “VAG”, the name by which the Volkswagen Group was formerly known.
VCDS will perform most of the functions of the expensive electronic diagnostic tools available only to official dealers, like the current VAS 505x series diagnostic tools. In the past, these dealership-only tools have prevented owners, and many small independent repair shops from performing some fundamental tasks, such as diagnosing problems, diesel ignition timing, modification of convenience options such as automatic door unlocking, coding a replacement electronic control unit (ECU) or key to the vehicle, and monitoring of many vehicle sensors for diagnosing problems. Unlike generic on-board diagnostics (OBD-II / EOBD), VCDS uses the more in-depth Volkswagen Group-specific manufacturer protocol commands, which allows the user to access all diagnostic capable vehicle systems — even in vehicles which are not covered by generic OBD-II/EOBD (e.g. pre-1996). In general, there are two ways to use this software, either as a package (software and hardware) distributed by the manufacturer or their agents, or, by building own interface hardware and using it with the public-available but limited shareware version of the software.
VCDS is also capable of interfacing vehicles which use the generic OBD-II/EOBD protocols. However, the OBD-II and EOBD standards only allow for limited diagnostics, and no adjustments to any of the ECUs.