Mercedes EZS/EIS Dumps for Sprinter W906, Vito W639 and VW Crafter: Lost Keys and EIS Swaps

A 2010 Sprinter 313 CDI, W906, has lost its only key and the EIS shows part number A9069003803 on the label. The owner’s insurer wants it mobile again this week. The dealer route means ordering a key against the VIN and, if the EIS turns out to be the reason the old key stopped working, a new EIS with an online personalisation appointment. The alternative starts with a dump of the ignition switch, and that’s what this post is about.

What the EIS is and what’s inside it

Mercedes calls it EZS (Elektronisches Zündschloss); the English documentation says EIS (Electronic Ignition Switch). On the Sprinter W906, the Vito W639 and the VW Crafter (which is a Sprinter underneath, EIS and all), it’s the module the key goes into, and it’s the centre of FBS3, the third-generation drive authorisation system. The engine ECU, the transmission controller and the electronic steering lock (ESL) are each paired to it.

The dump of its EEPROM contains, on most versions:

• the vehicle VIN and the SSID, the vehicle’s secret identity used in every FBS handshake
• the eight key positions, each with its own key data and a used, unused or disabled status
• the pairing data for the engine ECU, the TCU and the ESL
• the EIS password (in clear form on some processor versions, on others only recoverable by calculation)

The processor is a Motorola HC08 family chip on earlier units and a NEC on later ones, including most W906 and W639 from around 2008. The NEC units are the ones people mean when they talk about reading by infrared rather than lifting the chip.

All keys lost. Can a dump alone make a key?

Not by itself. To generate a working key you need the EIS password, and to get the password on a NEC EIS with no key you either read the EIS by IR together with the ESL (the ESL holds enough to calculate it on most versions), or you lift the NEC and read it on an adapter. Tools that do this: AVDI, Autohex, Zed-Full and VVDI MB all have all-keys-lost routines for W906 and W639. Once the password is out, the key file is calculated from it and the dump, and a blank key is written. The dump on its own gives you the VIN, the key count and which positions are free, which is useful before you quote the job.

The EIS itself is faulty. Can I fit a used one?

Yes, with a dump. A used EIS from a breaker belongs to another vehicle and carries its keys and pairings. The process is to renew it (write it back to a virgin state), then write your vehicle’s data into it: VIN, SSID and key data taken from the customer’s old EIS dump if it can still be read. If the old EIS is dead and unreadable, a renewed used EIS has to be personalised to the vehicle by Xentry online, and the engine ECU, TCU and ESL will need the same treatment because they’re paired to the old SSID. That’s the point where the cheap used EIS starts costing dealer money, so read the old one first, always.

Which part numbers?

A9069003803 is the W906 Sprinter and Crafter EIS we see most often. A9065456408 is an earlier revision found on W906 vans and the matching Crafter. Vito W639 numbers differ again. As always, take the number from the label on the module, not from a parts list; there are several revisions and the processor type isn’t always the same across them.

What goes wrong in practice

An EIS that reads fine by IR but refuses to accept a newly written key is usually one where the key position chosen was already flagged as disabled in the dump. Check the status bytes before writing, not after. An EIS that stops responding half-way through a NEC read is often a power supply problem on the bench adapter rather than a dead chip; the NEC is sensitive to a dip during the erase cycle, and if the erase completes without the write, you’ve got a virgin EIS you didn’t ask for, and you’re back to needing the old dump.

Then there’s the Crafter caveat. The VW-branded Sprinter uses the same EIS, but the engine ECU is a VW-coded EDC16 or EDC17 rather than the Mercedes part, and its pairing follows the Mercedes FBS logic anyway. VCDS or ODIS won’t help with the immobiliser side of a Crafter; Xentry or the key tools do.

If you already have the dump and need it decoded, a key file calculated, or a renewed dump prepared for a replacement EIS, upload it to the request form with the VIN and the part number. Our Mercedes immobiliser dumps sit in the immobiliser category, with the rest of the Mercedes-Benz range; for the general picture on immo work, read immo off explained.