How to Run and Save a VCDS Auto-Scan Before Diagnosis or Coding

To run a VCDS Auto-Scan, plug the interface into the car and the PC, switch the ignition on, test and save the port on the Options screen, then go to Auto-Scan, pick the chassis type that matches your car (or Auto Detect on newer CAN-only cars) and press Start. When it finishes, press Save before you close the window, because closing the Auto-Scan dialog throws away anything you have not saved or copied. Keep that saved scan: it is your record of fault codes and module coding before you change anything.

What an Auto-Scan is and why it matters

According to Ross-Tech's own Auto-Scan documentation, the function goes through each control module in turn and records its part numbers, component number, coding, workshop code and stored fault codes. In other words, it is a full snapshot of the car's diagnostic state in one text file.

That snapshot is useful for two things:

• Diagnosis. One scan shows every module that has stored faults, instead of you opening modules one by one.
• A backup before changes. The community guide on Audi-Sport.net about backing up a car with VCDS recommends saving the Auto-Scan before any coding or adaptation work, so you can go back if something goes wrong. That guide points out the Auto-Scan output also includes the long coding of each module, and the coding of some LIN sub-modules (such as a rain/light sensor) that do not appear in the module list on their own.

Before you start

Safety first. If you leave the engine running during diagnosis, do it outdoors or in a well-ventilated space, with the parking brake on and the gear selector in Park or neutral, and keep clear of moving parts. Never run diagnostics on a vehicle that is only supported by a jack.

Battery. A single Auto-Scan is short, but a longer session with the ignition on can drain the battery. The Audi-Sport.net guide notes that a full backup can take more than an hour and says the author connects a battery charger for that reason; the other options mentioned there are taking breaks to run the engine, or splitting the work over several sessions. Close all doors (without locking them) before you begin, as that guide also advises.

Interface and vehicle coverage. Ross-Tech's HEX-V2 product page says the interface connects to the PC by USB and to the car's OBD-II diagnostic port, and that it is intended for diagnostic-capable VW and Audi group passenger cars from 1990 onward, with some listed exceptions. The same page says USB extension cables must be active rather than passive. Check Ross-Tech's application information for your exact vehicle before relying on any result.

Step 1: Test and save the interface

1. Connect the interface to the PC and to the car's diagnostic port.
2. Switch the ignition on.
3. Start VCDS and open Options.
4. Select the port for your interface (with USB there is only one choice) and click Test.

Ross-Tech's Options screen documentation lists what a HEX-V2 should report: the CAN line as testing or OK, the K1 and K2 lines as OK, and both battery power (Vbat) and switched ignition power (VIgn) present at the diagnostic connector. If the test reports a short to ground or a short to +12V, Ross-Tech's page directs you to its instructions for testing the diagnostic port in the car.

5. Click Save. The Main Screen documentation explains that until the port settings have been tested and saved, every button except Options and About stays greyed out, so this step is required before you can scan.

While you are on this screen, Ross-Tech advises private users to leave the workshop code at 00000 and not to change the protocol settings unless they are having communication problems.

Step 2: Choose the chassis type

From the Main Screen, click Auto-Scan. Before you start the scan, select a chassis type.

Ross-Tech's Auto-Scan page explains that the chassis type tells VCDS which set of modules to look for, and that you should pick one containing only modules that could plausibly be fitted to your car. As a general rule it says the chassis type matches the 7th and 8th characters of the VIN. Its example is a VIN with "4F" in those positions, which corresponds to the Audi A6 C6. There is a search box to filter the list.

On newer cars that use CAN for all diagnostics, the same page describes an Auto Detect (CAN Only) option. VCDS then works out which modules are installed and scans only those, which is quicker. Older cars may need the chassis type chosen by hand, as the Audi-Sport.net guide also notes.

Step 3: Set the options and run the scan

Ross-Tech describes a few options on the Auto-Scan screen:

• UDS Aggressive Mode is on by default and tries to retrieve all fault codes, including some a factory tool may not display in every mode. Turning it off gives results closer to the factory tool's basic self-diagnosis.
• Display Freeze Frame Data adds the conditions recorded when a fault was stored, on modules that support it. Ross-Tech says leaving it on does no harm, but switching it off makes a scan with many codes easier to read.

Press Start. Ross-Tech warns the scan can take several minutes. You will see VCDS step through each module before returning to the Auto-Scan screen. Stop ends the scan early.

Step 4: Read the results

When the scan finishes, modules with stored faults are highlighted in red. Ross-Tech's page says you can double-click a red module to open its fault code screen. Where the module provides them, the scan also shows the VIN, engine code and component identifiers, so you can confirm the scan really came from the car you meant to scan.

Some lines in the output start with a symbol. Ross-Tech explains these refer to what coding information is available for the module (for example, whether a label file or only experimental coding information exists), not to faults.

Read and save the codes and freeze frame data before you clear anything, so the information is not lost.

Step 5: Save, copy or print the scan

Use the buttons at the bottom of the Auto-Scan screen:

• Save writes the scan to a text file in the VCDS Logs folder. Ross-Tech's example file name contains the VIN, the date, the time and the mileage, so scans from different days are easy to tell apart. The Audi-Sport.net guide gives the default folder as C:\Ross-Tech\VCDS\Logs, and says you can pick another folder when saving.
• Copy puts the output on the clipboard so you can paste it into a text editor or document.
• Print sends it to a printer.

Ross-Tech says newer VCDS versions also keep a copy of each scan in a Scans folder, typically C:\Ross-Tech\VCDS\Scans, even if you do not save it. It still recommends saving scans yourself somewhere safe, because files in that folder can be lost when you move to another computer or update. Copying saved scans to cloud storage or a USB stick is a sensible habit.

Two buttons are easy to confuse:

• Clear only empties the output box on screen. Ross-Tech is explicit that it does not clear any fault codes in the car.
• Clear All DTCs does erase fault codes from the modules. Ross-Tech says this is only available with a HEX interface. Only use it after you have saved the scan and dealt with the causes.

Close returns you to the Main Screen. Anything not saved or copied is gone at that point.

Common problems

• Auto-Scan button greyed out: the port has not been tested and saved on the Options screen yet. Go back to Step 1.
• Interface test shows a short: follow Ross-Tech's instructions for testing the diagnostic port, as referenced on its Options page.
• Modules missing or unexpected in the list: check you chose the right chassis type from the VIN, or try Auto Detect on a CAN-only car.
• Scan saved but cannot be found later: look in the Logs folder first, then in the Scans folder, and get into the habit of saving to a folder you choose.

Before you code anything

If you plan to change coding or adaptations, save a fresh Auto-Scan first and store it away from the laptop. The Audi-Sport.net backup guide goes further and also exports adaptation channels for each module to CSV files, and advises making no changes until the backup is complete. Keep your saved scans with the car's records so you can compare them later.

Sources

• https://www.ross-tech.com/vcds/tour/autoscan.php
• https://register.ross-tech.com/vcds/tour/option_screen.php
• https://register.ross-tech.com/vcds/tour/main_screen.php
• https://register.ross-tech.com/vcds/hex-v2.php
• https://audi-sport.net/xf/threads/324907/

Written by an AI agent from the sources listed above and not checked by a technician. Confirm against your vehicle service information before acting on it.