How to record a VCDS log: step by step

Updated: 2026-10-18

A VCDS log is a recording of the engine control unit's measuring values while you drive: boost pressure, air mass, ignition timing retard, mixture and many more. Most faults stay hidden while the car stands still. Lack of power, underboost or knock only show up under load. That is why mechanics and tuners ask for "a log of a pull": a dozen seconds at full throttle saved to a CSV file.

This guide covers what to prepare, how to record a log in Measuring Blocks and in Advanced Measuring Values, which groups to pick and which mistakes to avoid.

What you need

• VCDS with a Ross-Tech interface such as HEX-V2 or HEX-NET. The Turbo button, which speeds up sampling, only works with HEX interfaces.
• A laptop with a charged battery and sleep mode turned off.
• A second person. The driver drives, the passenger runs the laptop.
• A warm engine, oil at least 80 °C. A cold engine runs with reduced boost and fuel, so the log shows little.
• A safe place. Only do full-throttle pulls where it is legal and safe, ideally on a closed road or track.

Measuring Blocks: older control units

This is how you log TDI PD and VE engines, the 1.8T 20V or the 2.7 biturbo, i.e. ME7, EDC15 and EDC16 control units.

1. Plug the interface into the OBD port, switch the ignition on and start VCDS.
2. Click Select, then 01-Engine.
3. Choose Meas. Blocks - 08.
4. Enter the group numbers (up to three) and click Go! next to each. Check that the values refresh.
5. If the Turbo button is available, click it to sample faster.
6. Click Log and rename the file if you like, e.g. golf-011-3rd-gear.csv.
7. Click Start right before the pull. Click Stop after it.
8. Click Done, Close to close the file.

While recording you can click Marker. VCDS then writes a sequential number into the file, which helps you find, for example, the moment the car jerked.

Every extra group slows sampling down. According to Ross-Tech, two groups at once give about half the samples and three about a third. One or two groups are enough to check boost. Rather than three groups in one pull, do two pulls.

Advanced Measuring Values: newer control units

If VCDS shows Adv. Meas. Values instead of Meas. Blocks - 08 in the engine module, the car has a UDS control unit. That is the case for common rail TDIs, newer TFSIs and MQB cars, among others. Here you pick values by name instead of group numbers.

1. Click Select, 01-Engine and Adv. Meas. Values.
2. Tick the values in the list. VCDS allows 12, but each one slows sampling: with 12 values each refreshes roughly every 2 seconds, too rarely to catch a boost spike. 4–6 values are enough for a pull.
3. Tick Group UDS requests, which speeds up reading, and optionally Turbo. If the session drops or the values look wrong with Turbo on, leave the screen and come back without Turbo.
4. Recording works as above: Log, Start, the pull, Stop, Done, Close.

Value names differ between control units. Look for pairs of a specified and an actual value, e.g. for boost pressure, air mass and fuel rail pressure.

How to drive during the pull

• Gear: third gives a long enough pull. On a diesel with slow sampling, fourth works well too, because a longer pull means more samples.
• Start: around 1500 rpm on a diesel and 2000 rpm on a petrol engine.
• Full throttle up to around 4000–4500 rpm on a diesel or close to the rev limiter on a petrol engine. The pedal has to be floored. At part throttle the control unit asks for less and some faults will not show.
• Automatic gearbox: use manual mode so the gearbox does not downshift during the pull.
• Repeat the pull two or three times. A single pull can fail, e.g. because of traffic.
• Fault in other conditions? If the problem shows up at a steady motorway speed or at idle, record exactly that.

Which groups to log

Group numbers do not mean the same in every car. They depend on the control unit and its software. Below are typical examples. After recording, always check the column names in the file.

Example sets:

• TDI, lack of power: one pull with groups 011 and 003, another with group 008.
• 1.8T, lack of power: a pull with groups 115 and 118, a separate pull with group 020 (knock). Record group 032 at idle and during calm driving.

Where to find the log file

VCDS saves logs as CSV files in the Logs folder of the VCDS directory, by default C:\Ross-Tech\VCDS\Logs. If you do not rename it, the file is called e.g. LOG-01-011-003.CSV: the control unit address and the group numbers.

Common mistakes

• Too many groups at once. Sparse samples miss short boost spikes and dips.
• Cold engine. The control unit limits power until the engine is warm.
• Part throttle or a pull that is too short. A few seconds are not enough to see whether boost keeps up with the request.
• File opened and saved in Excel. With some regional settings (e.g. German or Polish) Excel saves CSV with semicolons and decimal commas, which other programs often cannot read. Send the original file from the Logs folder.
• A .bin file instead of a log. A .bin file is the control unit's memory (software and maps), not a recording of a drive.
• No label files. Without labels for the control unit, VCDS gives the columns generic names such as "(no units)" instead of "specified boost". The log is still useful but harder to read.

Frequently asked questions

How many groups can I log at once?

Up to three in Measuring Blocks and up to 12 in Advanced Measuring Values. The fewer, the denser the samples.

Is a log recorded at idle enough?

For some checks, yes, e.g. injector corrections at idle. Boost, air mass and ignition retard have to be checked while driving under load.

What do I do with the recorded log?

Send the original CSV file to your mechanic or open it on vaglogs. You get charts, a table and automatic diagnostics that check boost, air mass, ignition retard, mixture, fuel pressure and more. vaglogs recognises signals by their names and units, not by group numbers, so it reads logs from different control units and from VCDS in different languages.