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The VCDS Tool

Fault-find, log and program the modules in your Audi, VW, SEAT or Skoda

By Julian Edgar

Click on pics to view larger images

If you’ve got an Audi, VW, SEAT or Skoda, you may have heard of VCDS, previously called Vag-Com. VCDS is an interface that allows your laptop to communicate with the onboard control modules in your car’s electronics, including not just the engine management system but also modules for items like ABS, the instrument panel and so on.

So what can you do with the tool, how much is it, and how well does it work?

The Tool

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Produced by a company in the US called Ross-Tech, VCDS is physically a slightly enlarged OBD (on-board diagnostics) plug that contains the electronics, and a cable that terminates most commonly in a USB plug. As you’d figure from that description, the OBD plug is inserted into the car’s standard OBD socket and the other end of the cable plugs into your laptop’s USB port.

The software, which is specific to the VCDS system, is available as a free download from the Ross-Tech site.

The product is available in a number of versions but the most common (HEX+CAN USB interface) costs US$349. To Australia, postage was another $90 and it took about 2 weeks to get here.


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Software installation is very easy, with an unusually good leaflet that details what you should do if the device can’t find the right port, etc. Hardware installation requires just plugging the device in.

A self-test feature ensures the PC is communicating correctly with the car.

Main Screen

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The main screen looks like this.

The main buttons to know about are:

·       Select Control Module (you can go straight to the module you’re interested in – eg Airbags)

·       Auto-Scan (automatically looks at all modules fitted to the car and detects if there are any fault codes in them)

·       Service Reminder Reset (allows resetting of the service reminder)

·       OBD-II (detects standard OBD fault codes)

The Auto-Scan is the best starting point. After selecting your car from a dropdown list, the system scans the car’s electronics, finding the installed modules.  This is one way you can find out what is actually fitted to your car.

In the case of my car, a Skoda Roomster, the following modules were located and identified:

·       01 Engine

·       03 ABS

·       08 Auto HVAC

·       09 Central Electronics

·       15 Airbags

·       17 Instruments

·       19 CAN gateway

·       25 Immobilizer

·       44 Steering Assist

·       46 Central Convenience

·       76 Park Assist


Now it’s easy to start getting excited at this point – what, I can reprogram all the above 11 modules?! Well, yes and no.

VCDS is primarily a service tool: you get the feeling it replicates a lot of the functions of the factory service tool. And in the same way that the factory isn’t going to give dealer mechanics a heap of power over reprogramming these modules, neither does VCDS.

You can’t reflash the engine management for example, and the functions that VCDS does give you are often quite limited. Furthermore, often the programming approach isn’t clear.

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This is the screen you get when you access any control module. The buttons on the bottom left are for seeing live data and fault codes. On the lower right are buttons that allow you to make changes.

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For example, ‘Adaptation’ takes you to a screen where (in this case) changes can be made to engine idle speed. Note, however, that the approach isn’t particularly user-friendly: you have to insert a number than is then scaled to give an appropriate idle speed – rather than just enter the number in rpm.

Sometimes a security access code needs to be input before access to the module is allowed. Ross-Tech doesn’t provide this code.

By far the best VCDS reprogramming tips can be found on model-specific web discussion forums. I scoured these and while there are very few for the Roomster, because the Roomster uses some electronics common to other VW/Audi/SEAT products, I could get some clues.

Spending a very intense day researching online and using the VCDS in the car, I made the following changes:

·       Quietened the rear parking assist tone

·       Turned off ‘comfort clicks’ on indicator (where it flashes three times even when you’ve just brushed it)

·       Reduced auto off time for rear demister

·       Added ‘tear wipe’ function to washer/wipers (where the wipers do a final wipe 5 seconds after washing to remove drips)

·       Configured the instrument panel for Australia rather than Europe (this appears to add a seatbelt warning buzzer)

·       Reduced engine EGR

Now that sounds an impressive list until you realise that is absolutely all I could find to do that I actually wanted done! Not a lot of things for around 450 bucks.

But the story can be quite different for other cars. For example, some of the VW Golf models have literally dozens of widely documented functions that can be enabled or modified to suit the driver. But the Roomster, having a relatively simple suite of electronics, is much more limited.

Other Functions

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VCDS can also be used to register and reset fault codes…

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…reset the service indicator (and set what intervals it will appear at)…

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…code modules (required when adding a more sophisticated CAN gateway, adding cruise control or getting a new ignition key)…

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…and perform output tests (for example, the dashboard can be cycled through all its functions).


For a workshop specialising in Audi (etc) cars, I think it’s a brilliant tool.

But for the individual enthusiast? That depends on what you want to use it for.

If you want to reprogram in-car modules (the main reason I bought it), make absolutely certain that the programming functions that you want are actually available. If you can’t find reference to someone having done it on your exact model of car, it’s very likely it cannot be done. (And at the most, there appears to be only a handful of functions able to be programmed for any individual module.)

If you want to identify faults, reset the service indicator or read live sensor data from the ECU, VCDS works very well.

The tech support is also good, and the company website shows the functions of the tool clearly and with screen grabs.

Flush with cash? – buy it. Got a group of buddies all with VW, Audi, SEAT or Skoda cars? Share the cost and it would be a great buy.

VCDS does exactly what its makers claim… but the way it’s often talked about on the web, I’d expected it to do a lot more.

The product was bought for this story at retail price.

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