VAG ECU part number decoder: what ECU do I have?

Every Audi and VW ECU carries a part number like 06A 906 032 HS. Those twelve characters tell you the platform, the system, the exact unit and its revision, and they're the single most useful thing to know before you tune, swap or recover an ECU. Here's how to read yours.

Updated 18 September 2026 · decoder + 979-number reference

The three blocks

A VAG part number splits into three groups, sometimes written with spaces and sometimes run together:

• Block 1 — platform / engine family. 06A is the transverse 1.8T 20V and 2.0 8V family; 8E0 is the Audi A4 B6/B7; 1K0 is the Golf Mk5 platform. This is the part most people recognise.
• Block 2 — the system. 906 and 907 are engine electronics, 909 covers engine/immobiliser units, and 927 is the transmission controller. If you see 906 or 907, you're looking at an engine ECU.
• Block 3 — the exact unit, plus letters. The three digits identify the specific controller, and trailing letters (HS, AS, CG…) are the revision. These letters matter — two ECUs differing only by their suffix can carry completely different calibrations.

VAG platform prefixes (block 1)

The first three characters are the platform or engine family the part was first released for. VAG reuses them across brands, so a 06A ECU turns up in a Golf, an A3, a Leon and an Octavia.

Treat this as a strong indicator, not gospel: the same prefix can appear on more than one ECU family across model years. Confirm against the software number and the engine code before you flash anything.

System numbers (block 2)

The part number is only half the answer

Alongside the part number, every ECU reports a software number — something like 0002 on older units, or a ten-digit Bosch number like 1037383426 on newer ones. The part number identifies the hardware; the software number identifies the calibration on it.

How to find yours in 30 seconds

1. Over OBD (recommended). Plug in, connect to the engine controller, and read the identification block. The part number, software number and component name all come straight off the car — nothing to remove, nothing to risk.
2. Off the ECU label. If the car doesn't run, the sticker on the ECU carries the same part number. You'll need to get to the unit, which on most VAGs means the scuttle panel under the windscreen.

VAGPULSE reads both numbers for you the moment you connect, and tells you which Bosch family you're on and whether that ECU can be read and written over OBD.

Frequently asked

Can I fit an ECU with a different part number?

Sometimes, but it's the exception. A different suffix often means different software and different hardware expectations, and on component-protected cars the unit also has to be matched to the car electronically. See backing up your ECU before any swap.

My part number isn't listed — am I unsupported?

Not necessarily. The prefixes above are the common ones, not the complete set. VAGPULSE reads the real number off your car and tells you honestly what it can and can't do with that specific unit, rather than guessing from the badge.

Does the part number tell me if I can tune it?

It's the starting point. What actually decides it is whether that ECU's map locations have been verified on real hardware, which is why VAGPULSE switches tuning off, with the reason shown, on any file it doesn't recognise rather than applying another ECU's addresses and hoping.

What is the difference between 906 and 907 in an ECU part number?

Both are engine-control system numbers. 906 is used on most transverse and older units (06A906032, 038906019); 907 on Audi longitudinal and most diesel platforms (8D0907551, 4B0907401). 909 appears on some Audi engine ECUs (8E0909518). The 910 counterpart is the software number that pairs with a 906/907 hardware number.

What is the Bosch number and why does the tool show it?

Every Bosch ECU also carries a ten-digit Bosch number: 0261xxxxxx for petrol Motronic/ME/MED, 0281xxxxxx for diesel EDC. It is stamped in the file itself, so it is the number a tool can trust even when the label is missing. The decoder accepts either number.

Part-number reference by platform prefix

Every engine-ECU part number in the VAGPULSE stock library and file store, grouped by its platform prefix, with the Bosch number read from the file itself. 979 part numbers. Numbers marked store have a stock or Stage file in the file store.